Satellite Station 4.0 Part 11 – Phone Patch/Telebridge Capability

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Council Rock South Students Contact the ISS

Council Rock South Students Contact the ISS

I have joined the ARISS Program as a Mentor to help schools make contacts with astronauts on the International Space Station (ISS). School contacts as part of the ARISS program can take two forms – Direct Contacts and Telebridge Contacts.

ARISS Direct Contacts

Direct contacts involve setting up a space communications ground station at the school making the contact.

ARISS Direct Contact Ground Station Antennas at Council Rock HS

ARISS Direct Contact Ground Station Antennas at Council Rock HS

Direct Contacts involve a great deal of preparation and a local Ham Club which has considerable VHF weak-signal experience and equipment to partner with on a school’s contact. There can also be considerable expense involved in assembling the necessary ground station for a Direct Contact. In addition, some locations are much better than others in terms of access to good, high-angle ISS passes and an environment that is relatively free of nearby obstructions like buildings, hills, etc.

Our radio club, The Nashua Area Radio Society, supported a Direct Contact at Hudson Memorial School in December 2018. It was a fantastic experience. You can read more about what was involved here.

ARISS Telebridge Contacts

students at Maani Ulujuk High School in Rankin Inlet, Nunavut, Canada

Students at Maani Ulujuk High School in Rankin Inlet, Nunavut, Canada

Telebridge contacts involve using an existing ground station in a different location with an audio link to the school making the contact via telephone. This type of contact provides a high-quality experience with an astronaut on the ISS without the need to construct a ground station at the school. It enables the teachers involved in the contact process to focus on the educational aspects of their contact with the ISS.

All of the ARISS Telebridge Ground stations are built and operated to very high standards.

Also, schools in difficult locations or those who don’t have the needed support of a local Ham Radio club with the necessary space ground station equipment can still enjoy making a contact with an astronaut on the ISS. In addition, a Telebridge contact also enables the supporting Amateur Radio Club to focus on providing great Amateur Radio activities and educational support to their partner school.

Adding Telebridge Capability to Our Station

Space Communications Ground Station at AB1OC-AB1QB

Space Communications Ground Station at AB1OC-AB1QB

We’ve used the station here to make many satellite contacts and to listen to ARISS contacts from the ISS. We’ve also used our station to receive images from the ISS during ISS SSTV events. We’ve decided to add a Phone Patch to our station here to enable it to be used as a testbed for schools preparing for Telebridge contacts.

Adding A Telephone Patch

Phone Patch To Enable Telebridges

Phone Patch To Enable Testing and Hosting Telebridge Contacts

A Telephone Patch enables a third party to communicate over an Amateur Radio link using a telephone. A Phone Patch provides a connection between a Transceiver and a telephone line. It also handles creating a proper balance at the 2-wire Hybrid Interface that connects to the telephone line to the radio. A typical Phone Patch device also provides for Transmit and Receive level adjustments.

Phone Patch units are not used all that much anymore. Fortunately, MFJ still makes the MFJ-624E Hybrid Phone Patch.

Setting up the MFJ Phone Patch was pretty straightforward. All that was required to work with our IC-9700 Transceiver was to set the internal jumpers in the MFJ Phone Patch to configure its microphone connection properly. The MFJ Phone Patch had a cable connecting to the round microphone jack on the IC-9700 Transceiver. A connection between our audio amplifier to bring audio into the Phone Patch was made to complete the installation.

Testing On The Air

The MFJ Phone Patch was adjusted to achieve a good balance on the 2-wire Hybrid Interface to the telephone line, and the Transmit and Receive levels were properly adjusted prior to on-the-air use. These procedures are clearly explained in the manual for the MFJ-624E and are easy to complete.

With these steps complete, we set up a telephone call and made several contacts using FM stateless on the air. We received good audio reports and could easily understand the downlink audio using a standard telephone receiver.

Becoming an ARISS Telebridge Ground Station

My initial purpose for adding Telebridge capability to our ground station was to enable it to be used to perform testing of the audio systems in schools that will be hosting Telebridge contacts. I am also going to apply to become one of the ARISS Telebridge Ground Stations in North America. We have an emergency backup power system here, and our station’s location in our home makes it a good choice for situations where contacts need to be made at any time of the day or night. More to come on this in the future.

More About Our Ground Station

Here are links to some additional posts about our Satellite Ground Stations:

Fred, AB1OC

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