APRS Station Part 2 – Dedicated Antenna and Always-On PC

by

1

APRS Station Setup

APRS Station

We have had our APRS Station operating for a while now and it has been performing well. We decided to install a dedicated antenna on our tower that is a bit better matched to supporting our APRS Station. We choose a Diamond X50NA antenna and installed it on our tower at the 70 ft level using a vertical antenna bracket. The Diamond X50NA antenna has a broader vertical pattern than out existing repeater access antenna (a Diamond X300NA). The Diamond X50NA antenna is installed 19″ from the tower leg to minimize any interactions with the tower structure on the 2m band.

APRS Antenna On Tower

APRS Antenna On Tower

I also decided to move our APRSISCE/32 Software which controls our APRS Station to our home server which is always on.

Home Server

Home Server

The APRSISCE/32 software implements an iGate function (sending APRS packets to internet-based APRS servers) so it performs a critical role as part of our APRS Station’s operation. The following is a time-lapse video which shows about 6 minutes of the APRSISCE/32 software’s operation. The yellow lines show the paths taken by packets through various APRS Digipeaters on their way to the internet via our iGate. The circle on the map in the video is about 180 mi (290 km) in diameter. As you can see in the video, we are handing packets from New Hampshire, USA as well as from several surrounding states in New England. It is interesting to see the paths that some APRS packets follow as they find their way to the internet via our iGate node. It is quite apparent when there is an improvement in 2m propagation as we begin to see packets arriving from much greater distances.

The connection between our APRS transceiver (a Kenwood D-710A) and our home server is implemented via an RS-232 over TCP/IP device from StarTech. This device allows us to run the RS-232 control connection from the APRS transceiver to our home server over the wired Ethernet LAN installed in our home.

RS2323 Over TCP/IP Device

RS232 Over TCP/IP Device

With these steps, our APRS Station is complete. We are currently iGate’ing about 7,500 packets per month to the internet. You can see some real-time information on the performance of our station by clicking here.

– Fred (AB1OC)

Thank You For Helping Us Reach A Milestone!

by

0

Our Blog Readers Around The World

Our Blog Readers Around The World

As I write this, our Blog has crossed a milestone – we have readers in 100 countries around the world and our Blog has been viewed a little over 10,250 times. I just want to take a moment and thank all of our readers for your interest and tremendous response to our Blog. I also very much appreciate the encouragement and expressions of interest from many of our readers. Again, thanks very much to everyone.

We are planning to continue to provide new content here that we hope will interest and help our readers. Some of the posts in the works include more on setting up a station for the digital modes including JT65, WSPR and more, a second post on the completion of our APRS repeater, and posts covering a major expansion of our station as we automate much of  its operation via a system from microHAM.

– Fred (AB1OC)

Setting Up A Digital HF Station

by

6

Portable Digital HF Station

Portable Digital HF Station

I was looking back through a reader poll that I did some time back and noticed that a post on how to set up a Digital HF Station was pretty high on the interest list so I plan to cover that topic here. I have done quite a lot of digital HF operating over the past couple of years (approximately 4,000 Digital QSOs) and have had a lot of fun doing so. I hope to encourage others to give digital modes a try. I am going to break this post into four parts:

  • Why do digital HF?
  • What’s needed?
  • Digital HF Station setup
  • Digital HF operation

My goal for this post will be to introduce you to the digital modes and give a flavor of what is involved in getting set up to use them on the air in the HF bands. For those who decide to set up a Digital HF Station, I would recommend that you obtain a simple text such as the ARRL’s “Get on the Air with HF Digital” which gives a more in-depth explanation of what’s required to get on the air using the digital modes than I can provide here.

Why do digital HF?

Probably the biggest single reason to consider using the digital modes on the HF bands is that they can increase a station’s range without building new antennas and/or increasing output power. The more modern digital modes use narrowband signals along with error management techniques to increase the Signal to Noise (S/N) and error performance of a radio channel. In the extreme, modes like JT65 can be used to receive digital transmissions where the signal is at or below the noise floor! The digital modes on the HF bands present many good DX opportunities for modest digital HF stations. Early in my Amateur Radio career, I completed a DXCC Award using a simple Off-Center Fed Dipole antenna and a 100W transceiver over a period of about 6 months using the digital modes.

DXCC Award (Courtesy ARRL)
DXCC Award (Courtesy ARRL)

Some other reasons to try the digital modes include access to additional stations, a chance to work QSOs for operators who are hearing and/or speech impaired, and the opportunity to try a new mode of operation.

There are many different digital modes and discussing all of them is beyond the scope of this post (a good overview of the more common digital modes may be found here). The good news is that one simple hardware and software arrangement will put you on the air with a station that can do virtually all digital modes. For the beginning operator, I would recommend a focus on the Phase Shift Keyed (PSK) and Radio Teletype (RTTY) modes to begin with. These modes are by far the most commonly used and both provide good performance with a modest station. PSK is a modern mode and is probably the best performing of the digital modes for general purpose 2-way digital communications. RTTY is an older digital mode (one of the first to be used in Amateur Radio) and is still widely used by DXpeditions and in contests as well as for general digital communications.

What is needed?

The first step is to setup a simple SSB phone HF station. One does not need to build a big or complex station for digital HF operations – a 100W transceiver and a dipole or vertical antenna will provide plenty of fun for the digital HF operator. Most digital communications take place using only 25 – 75 watts of power so a 100W transceiver is more than adequate. Digital HF modes also work well using QRP power levels. In addition to a basic SSB HF Station, you will need a Personal Computer (PC) that will run a software program to decode the information in digital signals received by your transceiver and to generate the properly modulated audio signals and key your transceiver to enable you to transmit digital information on the HF bands. Those of you who have used HF modems over dial-up telephone lines to access the internet has already used essentially the same techniques that are used to transmit and receive information using the digital HF modes.

Dial-up Modem (Courtesy Wikipedia)

Dial-up Modem (Courtesy Wikipedia)

The only differences are 1) an Amateur Radio HF SSB transceiver is used to create the audio path instead of a telephone line, 2) the PC plus a sound card is doing what the dial-up modem did, and 3) you are communicating directly with another Amateur Radio Operator with a similar setup to yours instead of an Internet Service Provider.

A basic laptop or desktop PC running Windows or Mac OS X is all that is required to run a Digital HF station. The PC should be modern enough to run Windows XP or Windows 7/8 or the recent versions of Apple’s Mac OS X. The Linux OS is also a possibility.

PC For Digital HF Station

PC For Digital HF Station

Most PCs sold within the last 5 years or so have plenty of computing and storage capacity for this purpose. I would also recommend a PC that has at least two USB ports and some sort of connection to the internet for call sign information lookup and possible spotting network access. You should also ensure that your PC is stable and in good working order before you try to use it to operate your digital station. While the digital modes and the associated software are not particularly demanding of your PC, it will be an essential part of completing digital QSOs and you do not want to begin with an unstable PC that locks up or crashes frequently.

To complete your Digital HF Station, I would recommend the use of an external sound card and a rig control interface cable. While these latter two items are not essential (you can get by with the PC’s internal sound card and no rig control interface), I recommend an external sound card and a rig control interface for several reasons. First, an external sound card makes it easier to set up and adjust audio levels for proper operation (more on this later) and it generally provides a little better performance than a PC’s internal sound card. While not essential, a rig control interface cable will automate important aspects of logging, changing bands, and tuning through the digital sub-bands and is not particularly expensive or complex. I have found both of these additions to be very useful enhancements to a Digital HF Station.

There are many different choices for sound card setups for Amateur Radio use ranging from basic radio interfaces which use the PC’s internal sound card all the way to some very high-end units that support radios with dual receivers and have built-in rig control interfaces. Manufacturers and devices to look at include West Mountain Radio’s RigBlasters, Tigertronics SignaLink USB, US Interface’s Navigator as well as others. For the beginning digital operator, I would recommend the SignaLink USB from Tigertronics.

SignaLink USB (courtesy of Tigertronics, Inc.)

SignaLink USB (Courtesy of Tigertronics, Inc.)

The SignaLink USB is inexpensive and is available in kits that include the proper radio cable and configuration jumper blocks for many different radios. It is compatible with all of the popular digital software packages and performs well. It is widely available from distributors like Ham Radio Outlet and many digital operators are familiar with it and can provide help in getting you on the air.

For rig control, I would recommend a USB to radio control cable from RT Systems if one is available for your transceiver (this is the same cable that is used to program the radio using RT System’s software) .

RT Systems Radio Cable (Courtesy RT Systems, Inc.)

RT Systems Radio Cable (Courtesy RT Systems, Inc.)

These cables provide a connection between your radio and your PC that allows the digital software to read the radio’s frequency, tune the radio within a digital sub-band or change bands. While these features are not strictly necessary for digital operation, I find that they make the operating experience for the beginning Digital Operator simpler and more enjoyable and are well worth the small added expense and effort.

Finally, there is the question of Software. Again there are many choices here. I have used two and can recommend both of them:

Both of these packages can support all of the popular digital modes, logging of QSOs and Rig Control for digital operations. HRD is a more complete package that includes a full set of logging capabilities, award tracking, spotting cluster access and integration, rotator controls, etc. Fldigi is more of a digital modem program with basic logging capabilities. There is also a native version of Fldigi for Mac OS X and for Linux (although you can run HRD on a Mac using VMware Fusion or Parallels. Personally, I have mostly used Ham Radio Deluxe/DM780.

Digital HF Station Setup

The first step in setting up your Digital Station is to connect your radio to your PC. The figure below shows the connections which are required (this is the configuration we use for our portable Digital Station)

Digital HF Station Configuration

Digital HF Station Configuration

The exact set of steps required to set up and configure a Digital Station will depend on the specific combination of radio, sound card, PC, and software used. How-to books like ARRL’s “Get on the Air with  HF Digital” are good sources of information on how to perform these steps as are the equipment manufacturers’ websites and manuals. The steps required are not complex or difficult but a little help the first time that you do them can be helpful and seeking assistance from an Elmer who has experience with Digital HF is a good idea. Here are a few general suggestions to keep in mind as you set up your Digital Station:

  • If your radio has dedicated “DATA” or “ACC” jacks to connect audio to a sound card, these are usually the best way to go. If you use the microphone and speaker/headphones connections, be sure you disable the speech compressor and audio equalization when operating using the digital modes.
  • Pay close attention to the instructions related to the installation of drivers for your sound card and rig control cables as the order of doing these steps can be important. Also, be sure that the sound card associated with your radio is NOT your default sound card for your PC or you may put unintended audio over the air.
  • Be sure to adjust you transmit and receive audio levels properly so that your digital station performs well and does not emit spurious signals or splatter on the air when you transmit. Your sound card and digital mode software manuals will explain how to do this.

Digital HF Operation

Digital QSO In Progress

Digital QSO In Progress USing HRD/DM780

With the setup steps complete, the fun of Digital HF Operation can begin. Both Ham Radio Deluxe and Fldigi provide many features that make digital mode operation easier. These programs include macro capability that will automate many aspects of most QSOs such as calling CQ, responding to a CQ call from another station, providing station and other information, and closing and logging a completed QSO. It is a good idea to take some time to understand the use of your software’s macro capability and to customize your macros with your call sign, station information, etc.

I would recommend that you begin with the PSK digital mode as it is easy to use, very popular on the HF bands, and will generally perform best. Also, take some time and review the applicable band plan for your country as there are specific sub-bands allocated for digital mode operations. An example of the United States may be found here. The most active areas for PSK traffic in the United States will generally be in these frequency ranges:

HF Band Frequency Range
160 m 1.838 – 1.848 MHz
80 m 3.580 – 3.590 MHz
40 m 7.035 – 7.045 MHz
7.070 – 7.080 MHz
30 m 10.140 – 10.150 MHz
20 m 14.070 – 14.080 MHz
17 m 18.100 – 18.110 MHz
15 m 21.070 – 21.080 MHz
12 m 24.920 – 24.930 MHz
10 m 28.120 – 28.130 MHz

Common Frequencies for PSK Operation

Finally, take some time and experiment with the IF/Roofing filters and Noise Reduction features on your transceiver if you have them. These features, when used properly, will often reduce errors in receiving weak digital signals or help you to better deal with the negative effects of strong digital signals near your operating frequency.

I am considering a future post to cover digital operations using JT65 and WSPR on the HF bands. These modes operate and very low power and in marginal conditions and can be used to complete QSOs over marginal paths and to measure your station’s performance in real time. Please post a comment on this blog or drop me an email if you are interested in these modes. If there is enough interest, I will provide a post on these topics in the near future.

I hope that this post has helped to spark your interest in operating using the Digital Modes on the HF bands. I hope to work you on the HF bands using a digital mode soon!

– Fred (AB1OC)

Site of the Day – K9CT Contest Station

by

0

One of our readers Craig, K9CT has built a very nice Contest Station. The above video is an overview of his station’s antenna farm – well worth watching! Craig also makes use of Stacked SteppIR antennas in his setup and his station features an 80m yagi as well as a 160m vertical array. I think many of our readers might enjoy taking a look at the K9CT contest station website. Check it out via K9CT Contest Station.

– Fred, AB1OC

AB1OC Learns CW, Enters The 2012 CQ WW CW Contest QRP

by

2

CW Paddles

Bencher CW Paddles

The past few weeks have been good ones in terms of progress on some of my operating goals. An important one since the very beginning of my involvement in Amateur Radio has been to learn morse code and to operate CW. Many folks have made good suggestions on how to go about learning the code and I used a combination of these suggestions to get to the point where I am now. The first tool that I used was Code Quick to learn the alphabet and get some initial practice. This course is a good one because it uses the Farnsworth Method to teach the sounds of the letters and discourages thinking in terms of “dots” and “dashes” which severely limits one’s ability to copy code at speed. The second tool that I used was Gordon West’s Morse Code CDs to get some practice copying sentences and words. The final tool that I used was W1AW’s Practice Code Files to get some additional training on copying sentences and words.

The Thanksgiving Holiday here in the U.S. afforded me some time to really practice hard for several straight days and I finally got to the point where I was able to make a few QSO’s on the air. My first was CW QSO was with K4JYS, Bill in North Carolina on 160m. Bill must be one very patient Op as a combination of nerves and very limited CW skills made my first QSO pretty difficult. I did a few more QSOs over the next few days after some more practice, I improved my skills a bit more (I also completed about 30 QSOs with my dummy load to practice my sending skills. I am awaiting QSL cards from these QSOs to complete my WADL – Worded All Dummy Loads – Hi Hi).

Anita (AB1QB), my XYL after observing all of this, suggested that I enter the CQ WW CW Contest. At first, I thought that this was not practical given my limited CW skills. Later that evening, I was reading through the manual for my Elecraft KX3 Transceiver and noticed that it had a built-in CW decoder. I headed to the shack to try this out and found the KX3’s CW decoder to be excellent. After a little thought, I decided to enter the contest with the assistance of the KX3’s decoder to get some more practice copying CW on the air. After some thought, I settled on entering the contest in the single band 10m QRP category unassisted. I chose this category for several reasons. First, 10m only operation was positive in two respects – if the band was open it would make my 5 watts QRP go much further than 5 watts on the lower frequency bands and second 10m would be out at night which would give me a chance to take a break from my crash course in CW and get some sleep. I choose the unassisted category because I wanted to learn to tune through the band looking for CW signals and I choose QRP in the hopes that the contest would help me towards my goal of working a DXCC Award QRP.

CQ Zones (Courtesy CQWW website)

CQ Zones (Courtesy CQWW website)

The CW WW CW Contest score is a combination of points from QSOs worked, Countries worked, and CQ Zones worked. My final count for the contest  (all on 10m using 5 watts) was 125 QSOs, 49 Countries and 20 CQ Zones worked. This brought my total DXCC QRP Count to 83 Countries worked – within striking distance of the award. I worked 24 new Countries’ QRP that I did not have before the contest, with several being all-time new ones!

The best part of working the contest was the practice I got listening to higher-speed CW. Most contest operators work at about 25 words per minute or higher speeds and it was a real challenge to copy code this fast in the beginning so I had to rely on the KX3’s decoder. After a while, I learned to “hear” the sound of commonly used words in the QSOs like “CQ”, “5NN”, “TU”, and my call sign. I think the practice from the contest really helped my ability to copy CW at more realistic speeds. While it probably seems like diving into the deep end of the pool, I can recommend working a CW contest with the aid of a decoder as a good tool to help learn CW. There is nothing like running a lot of QSOs to help improve operating skills and I doubt that I would have 150+ CW QSOs under my belt at this point without participating in the contest.

I am continuing to practice CW and complete QSOs on the air. While I am a long way from where I want to be as a CW Op, I am very happy to have gotten to this point. Interested in some history of Morse Code? Check out this article that Nicole, a student in Wyoming has created.

– Fred (AB1OC).

Contesting QRP Style – The 2012 ARRL Phone Sweepstakes

by

0

KX3 Using Guest Position

KX3 QRP Rig

One of my goals has been to complete a Worked All States Award (WAS) QRP. We added an Elecraft KX3 Transceiver to our station recently to facilitate achieving this goal and to equip ourselves with a lightweight portable “travel” radio. When the 2012 ARRL Phone Sweepstakes came around a week or so back, I decided to use the combination of the KX3 and our new antenna system to try to achieve a WAS award QRP and to have a little contesting fun in the process.

I did a bit of on-air testing before the contest and got some pretty interesting results. As an example, I worked a QSO with KC0W, Tom in Minnesota, USA (about 1,550 miles from my QTH) using 5 watts peak power and got a signal report of 59 + 10 dB. After letting Tom know I was QRP he asked me to drop my power to 1 watt. I did so and received a signal report of 59. At this point, Tom was pretty amazed and asked me to drop my power again so I went as low as the KX3 would go which was 100 mW. Tom then gave me a 57 signal report and we proceeded to have a nice rag chew. These results gave me some encouragement to work the contest QRP.

2012 ARRL Phone Sweepstakes Results for AB1OC

2012 ARRL Phone Sweepstakes Results for AB1OC

I was not able to work the entire contest period due to other commitments. As you can see from my multiplier tracking sheet above, we came pretty close to our goal of completing a QRP WAS during the contest – 42 of the 50 states worked and most of the contest multipliers snagged. I made 130+ QSOs during the limited time that I had to operate. I have since worked a few additional states QRP and now only need 4 to complete a WAS QRP – Montana, North Dakota, Oklahoma and Utah. The first two are the difficult ones that remain and I should be able to get there with a little more work on the air.

If any of our readers living in one of the states that remain to complete a WAS QRP and could help me complete a QSO, please drop me an email at ab1oc@arrl.net

– Fred (AB1OC)

APRS Station Part 1 – Station Radio And Software

by

1

.We recently became interested in the Automatic Packet Reporting System that is used over Amateur Radio. This system is primarily used on the 2m Band. it can report position, weather, emergency information, telemetry, and other data over a shared RF channel. The traffic on the Amateur Radio APRS network originates from a variety of sources including mobile VHF radios (FM and DSTAR), HTs, Weather Stations, Personal Computers, and more recently, smartphones. APRS uses a combination of the Internet and the 2m (and 70cm) radio bands to transport position and other information over RF to gateway ports to the Internet. The data is consolidated and displayed on sites like aprs.fi.

APRS Station

We decided to set up a station in our shack so that we could learn about APRS and its applications. We selected a Kenwood TM-D710A Transceiver for our radio. Kenwood is a leader in APRS technology and they incorporate the necessary AX.25 Terminal Network Control (TNC) in several of their radios including the TM-D710A. We added an AvMap G6 GPS to the base radio to provide a local display of the information that is received over the air. We also made use of our Diamond X300NA antenna to test our station. This antenna is up about 50 ft and provides a decent level of gain (6.5 dB) for APRS work. While this antenna has a fairly low pattern designed for repeater access work, it turned out to perform well during the initial testing of our station.

Diamond XA300NA Antenna

Diamond X300NA Antenna

The first step in getting the station on the air was to program the TM-D710A as an APRS Digipeater. A Digipeater listens to the shared APRS radio channel (the 2m APRS frequency in the United States is on 144.390 MHz FM). When an AX.25 APRS packet is heard, the Digipeater’s TNC decodes the packet, displays it on the local radio (and an attached display or PC if available), and then decides whether to retransmit the pack so that other stations further away from the source can also receive it. APRS has used a number of protocols for Digipeating since its inception. The current protocol is called WIDEn-N. The WIDEn-N protocol uses a Time To Live mechanism to ensure that packets are only propagated a limited number of hops before they are discarded. It also provides tracing so that the source of a packet and the route that it has taken can be determined. Kenwood has a good document that explains APRS Digipeating and how to set up the TM-D710A to operate as a Digipeater. The following picture shows our station operating in Digipeater mode and provides an example of packets as they are received and displayed. The AvMap G6 GPS is a nice accessory for an APRS station as it displays the received APRS packet information on a map display. In a mobile setup, the AvMap can also provide “dead reckoning” navigation based on a station that is also mobile. The AvMap will calculate an intercept path based on its location and a target station accounting for the speed and direction that both stations are moving in.

APRS Station List Display

Station List Display

APRS packets contain a good bit of information about the station originating the packet. In addition to the GPS coordinates where the packet originated, packets may contain telemetry or other information from the originator. The picture below shows a packet from a weather station connected to a transceiver. As you can see, the current weather conditions at the source are contained in the packet and can be displayed on the Kenwood TM-D710A.

APRS Weather Station

APRS Weather Station

The APRS system also provides for the transmission of short messages and eMail to and from radios and client devices such as PCs or smartphones. The following picture shows an example of a short message sent to our APRS base station from one of our iPhones. APRS provides for Secondary Station Identifiers (SSIDs) which allow multiple devices owned or operated by a single call sign to be separately identified. In our case, we have the set up of the following devices so far:

  • AB1OC-10 – our base station
  • AB1OC-7 – an APRS HT
  • AB1OC-9 – Fred’s iPhone running an OpenAPRS client (search for “OpenAPRS” in the iTunes Store)
  • AB1QB-9 – Anita’s iPhone running the OpenAPRS client
APRS Message Reception

Message Reception

Portable Station

To complete our system, we also purchased a Kenwood TM-D72A HT. This unit also has a built-in AX.25 TNC and a GPS making it an ideal tactical station for emergency and other public service work.

APRS HT

APRS HT

Adding iGate Capability

The second step in setting up our station was to create an APRS Internet Gateway or iGate. An iGate is a radio node that is attached to an Internet-connected computer for the purpose of getting packets on and off the Internet. In most APRS networks, an iGate node is the last step in the radio path between an APRS client device like a mobile radio and the Internet. Once the packets find their way to an iGate, the iGate is responsible for routing the packets using the Automatic Packet Reporting System-Internet Service protocols to an APRS-IS tier 2 server. The Tier 2 Servers are typically deployed regionally and handle the process of distributing the worldwide load of APRS packets to the iGates. The packet processing and routing of the Tier 2 Servers are coordinated by a set of Tier 1 APRS-IS Servers. This two-level structure is required to efficiently and reliably handle the massive load of packets that are routed worldwide. Other non-radio-oriented services which use APRS protocols such as Citizen Weather Observer Program (CWOP) and OpenAPRS can also interface with the APRS-IS Servers.

iGate Clients

There are several APRS clients that provide iGate functionality. We selected the APRSISCE/32 software provided by KJ4ERJ to implement our iGate. We chose APRSISCE/32 because it has an active developer and support community, is feature-rich, provides a good user interface including nice map displays, and is compatible with the Windows 7 platforms that we use. Other popular choices include UIView, WinAPRS, and several other programs. APRSISCE/32 has a good Wiki that explains the program and how to set it up. The Wiki plus the APRSISCE Yahoo Group were all we needed to get our iGate up and running. There is also a user manual for the software that is available here.

APRS Path - Northern New Hampshire

APRS Path Shown in APRSISCE/32 – Northern New Hampshire

The APRSISCE/32 Software combines packet information received by the APRS base radio with packets routed over the internet from the APRS-IS servers and combines this information on a map display. APRSISCE/32 can also interface with the CWOP servers to obtain and display weather station information as well. The software includes iGate functionality which will intercept packets on the RF side of the network and route them to the Internet. It can also selectively route packets on the Internet portion of the network over the air. Obviously, one must be careful to be selective about routing APRS-IS Internet packets over the air as a single poorly configured iGate can completely overload a regional APRS network! In our case, we choose to route position information from our two iPhones (AB1OC-9, and AB1QB-9) to the RF side of our iGate. In the future, we plan to route packets from our Weather Station on CWOP once the necessary filtering is available in APRSISCE/32. APRSISCE/32 can show the RF paths to our iGate in real time as packets are routed from RF clients to the Internet. The picture above shows the RF path taken from a station in Northern New Hampshire to our Station and its associated iGate. The picture below shows the path from a station on Cape Cod, MA to our iGate.

APRS Path - Cape Cod, MA

APRS Path Shown in APRSISCE/32 – Cape Cod, MA

The APRS system is quite adaptable. It can find a path to the Internet based on the availability of Digipeaters, iGates, and the current RF propagation conditions. This behavior makes APRS a perfect tool for coordinating emergency operations and it is used as part of RACES and ARES activities.

APRS Applications

There are a number of interesting applications that are built on the APRS platform. One of these measures VHF propagation in real-time. Measurements are based on the paths that stations and Digipeaters use to propagate APRS packets. This information is available in map form here.

2m Propagation in the Northeastern USA

2m Propagation in the Northeastern USA

APRS.fi Website

Another useful site is the aprs.fi site. This site provides maps and route displays for mobiles, weather stations, Digipeaters, etc. The picture below shows an example of a mobile unit’s route display as it moves through our area.

Route Display

APRS fi Route Display

APRS fi can also provide detailed information about the packet traffic associated with a given station. An example of this information is shown for our APRS iGate/Digipeater below.

Snapshot for AB1OC-10

APRS fi Details for AB1OC-10

At this point, we have completed the first phase of our station and it is fully operational. Next, we will be installing a dedicated antenna for our station on our tower.  We will also move our iGate software to an always-on PC. We plan to provide a future post on these upgrades.

– Fred, AB1OC

QRP Operation With New Antennas

by

0

KX3 Using Guest Position

KX3 Using Guest Position

One of the things that I have been interested in doing for a while is working a DXCC Award QRP (using low power). I took some time to set up our guest operating position in the shack this weekend and decided to hook up our new Elecraft KX3 QRP radio there to test some QRP operation with our new antennas. The guest position in our shack is designed to provide easy hookup for a transceiver brought by a friend to our shack. It has full access to all of our antennas and the same band filtering that our other operating positions use allowing a guest operator to use the shack at the same time that we are operating.

The guest position has access to our SteppIR DB36 4 over 4 array on our tower and I decided to try these antennas operating as an array on 40m QRP.  The results were better than expected. I was able to work a good bit of DX including DK1NO (Germany), 8R1Z (Guyana), D4C (Cape Verde), YY2CAR (Venezuela), and HE5LC (Switzerland) as well as a number of stations in the United States. Most of the DX stations gave me 59 or 59+ signal reports and a few of the US stations in the southeast an midwest gave me signal reports of 59 + 10 dB! This was more that I expected operating SSB QRP. My total worked country count operating QRP now stands at 35 with the longest QSO being about 5,250 mi. I think I should be able to achieve a DXCC QRP with a reasonable amount of effort, some good band conditions and the new antennas.

The Elecraft KX3 is a great QRP rig. The receiver is excellent with good sensitivity, decent selectivity and good noise reduction and filtering capabilities. It also appears to provide a good deal of operating time when run on batteries. The rig puts out up to 10w peak in SSB mode on batteries and will run up to 12w if externally powered. The KX3 also provides very good quality audio in SSB mode. This will be my go to rig for QRP operation going forward.

– Fred (AB1OC)

Tower CAM

by

5

Tower CAM In The Shack

Tower CAM In The Shack

After our recent experience with Hurricane Sandy, we learned that its important to monitor the impact that high winds are having on our antennas so that they can be pointed to minimize wind loads. We cannot directly see our antennas from inside our shack where our rotator controllers are located so this involved many trips up and down the stairs between our shack and the outside where we can see how the antennas are doing in the wind. To solve this problem, we decided to take advantage of the Video Monitor that is installed in our shack and install a camera that lets us view our antennas on the tower from inside the shack.

There are many closed circuit security cameras on the market that are designed for close range surveillance of entry points but it is more difficult to find a camera that does a good job at the 100 ft+ distance between our house and the antennas on our tower. After some research, we settled on a Long Range Outdoor Security Camera from LOREX. This camera has a lens that is well suited for longer range viewing and also features higher resolution and frame rates than most security cameras. The first step in the installation was to install the camera in a sheltered area on our house facing the tower.

Tower CAM

Tower CAM

Mounting the camera so that it would look up at the antennas was a bit of a challenge (most security camera mounts are designed to look down, not up) but we were able to work this out after some experimentation. It was then an easy matter to run the single cable which caries both the video signal and power from the camera to the Video Monitor in our shack. As you can see from the video which follows, the setup worked out pretty well and we can now see what our antennas are doing from inside our shack. It’s also nice to be able to monitor the rotation of the antennas when we are operating.

– Fred (AB1OC)