Amateur Radio Station Design And Construction

Station Design And Construction

Station Design And Construction

A little ways back, John (W1MBG) discovered our Blog and approached us about doing a presentation for the Nashua Area Radio Club (NARC) on the design, construction, and operation of our recently completed station. The NARC group invited us to their March meeting where we shared our presentation with the nice group of folks in the Club. I wanted to post an overview of what we shared as well as a link to the full presentation so that our readers can have a look at the material and hopefully benefit from the information that we have assembled. I have also used this post as an opportunity to create an index to all of the articles on this Blog related to the design, construction, and performance of our station.

Topics Covered

Topics Covered

Our new station project involved both the construction of a dedicated room for a new shack and a tower-based antenna system. It took us about 1 1/2 years to build our station including the associated antenna system and we covered quite a number of areas during the project. Our presentation focused on some things that we did to plan and build our station that should be useful to many Hams building or upgrading anything from a simple station to an all-out effort to create a state of the art multi-op station.

Station Goals

Station Goals

I think that it’s important to begin a new or upgrade station project by thinking through and writing down the goals that you have for your new station prior to purchasing equipment or beginning construction. This step is important because it helps you to think through what you want to accomplish and serves as a high-level blueprint for making the design, equipment selection and construction decisions as you build your station.

Shack Layout

Radio Shack Layout

We put considerable time and thought into the design of the room and operating area for our new shack including many rounds of drawings and some “human engineering” to arrive at the final room layout. While not every Ham will build a dedicated room for their shack, some careful thought put into the layout of the operating and storage areas for your shack and the associated support systems is an important design step.

Antenna System Planning

Antenna System Planning

The other major element in the design of our station was a new tower-based antenna system. We had some pretty expansive goals for the band capabilities and associated performance of our new antenna system and the presentation explains how we went about developing and executing a plan to meet our goals.

Additional Antenna Construction

Additional Antenna Construction

Since the initial installation of our tower antenna system, we added an 8-Circle Vertical Receive Array for the Low Bands and we’ve reinstalled our SteppIR BigIR Vertical Antenna. These new antenna systems provide important additional performance on the low bands and during contests. We’ve also added an Antenna System and Electronics for LEO Satellites.

Station Automation

Station Automation

We’ve also installed an SO2R and Station Automation System from microHAM. The microHAM system enables much smoother and less error-prone operation of our station and enables SO2R and Multi-two operation during contests.

Virtual Station Tour

Virtual Station Tour

Our presentation includes several slides that cover the construction of our new shack and tower as well as the feedline, antenna, power, and other supporting systems. The end result of all of this work is shown via a few slides that provide a “Virtual Tour” of our station.

Virtual Station Tour - Operational Videos

Virtual Station Tour – Operational Videos

The “Virtual Station Tour” slides contain several videos. You can play these videos below.

Upper SteppIR Beam Rotating

Other posts in this Blog contain more detailed information and many additional pictures and videos about our station. See the index of links at the end of this post to view more detail about the areas that interest you.

Station Performance

Station Performance

Our new station has been complete for several months now and we wanted to take some time to look at how it is performing against our original design goals. As you can see from the above slide, we are on a good track to meet or exceed all of the original goals that we set during the planning stage of our project.

What We Learned

What We Learned

Finally, we shared some additional information about what we learned during the project and a set of links to various sources of equipment and information that we used to complete our new station (see the full presentation). This Blog contains many more details (and pictures) about the design and construction of our station for those who are interested. Some good places to begin are categorized in the index of links below:

Shack Design and Construction:

Antenna and Tower Design:

Tower Construction:

Antenna Construction:

Tower Integration:

Station Integration:

Station Operation and Performance:

I hope that you can apply some of the ideas and information shared here to building or improving your station. We’d also like to extend a special thanks to John, W1MBG and the NARS Group for encouraging us to create and share this presentation. We are available to provide this presentation to other clubs or Ham gatherings. If your club or event is interested, please contact us at ab1oc@arrl.org.

Fred, AB1OC

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

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)

APRS Station Part 1 – Station Radio And Software

APRS Station Setup

APRS Station Setup

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 to 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, smart phones. 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.

We decided to set up an APRS station in our shack so that we could learn about APRS and its applications. We selected a Kenwood TM-D710A Transceiver for our APRS base 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 APRS station information that is received over the air. We also made use of our Diamond X300NA antenna to test our APRS 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 APRS 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 channel 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 APRS packets are only propagated a limited number of hops before they are discarded. It also provides tracing so that the source of an APRS packet and route that it has taken can be determined. Kenwood has a good document which explains APRS Digipeating and how to set up the TM-D710A to operate as a Digipeater. The following picture shows our APRS station operating in Digipeater mode and provides an example of APRS 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 APRS setup, the AvMap can also provide “dead reckoning” navigation based to an APRS station that is also mobile. The AvMap will calculate an intercept path been its location and a target APRS station accounting for the speed and direction that both stations are moving in.

APRS Station List Display

APRS 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 was originated, APRS packets may contain telemetry or other information from the originator. The picture below shows a packet from a weather station connected to an APRS 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 APRS 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 allows multiple devices owned or operated by a single call sign to be separately identified. In our case, we  have the following APRS devices setup so far:

  • AB1OC-10 – our APRS 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

APRS Message Reception

To complete our APRS 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 APRS station for emergency and other public service work.

APRS HT

APRS HT

The second step in setting up our APRS station was to create an APRS Internet Gateway or IGate. An IGate is an APRS radio node that is attached to an Internet connected computer for the purpose of getting APRS packets on an off the Internet. In most APRS networks, an IGate node is the last step in the radio path between and APRS client device like a mobile radio and the Internet. Once the APRS packets find their way to an IGate, the IGate is responsible for routing the APRS 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 world-wide load of APRS packets to the IGates. The packet processing and routing of the Tier 2 Servers is 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 APRS packets that are routed world-wide. Other non-radio oriented services which use APRS protocols such as Citizen Weather Observer Program (CWOP) and OpenAPRS can also interface to the APRS-IS Servers.

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 UIViewWinAPRS 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 APRS 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 side of the APRS 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. One of the cool things about APRSISCE/32 is that it 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 APRS Station and it’s associated IGate. The picture below shows the path from a station on Cape Code, MA to our IGate.

APRS Path - Cape Cod, MA

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

As you can see from these screen shots, the APRS system is quite adaptable and can find a path to the Internet-based upon 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.

There are a number of interesting applications that are built on the APRS platform. One of these measures VHF propagation in real-time based upon the paths that the APRS 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

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

APRS fi Route Display

APRS fi Route Display

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

APRS fi Snapshot for AB1OC-10

APRS fi Details for AB1OC-10

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

– Fred (AB1OC)