It is very rare to hear clear CW from the AO-7B telemetry beacon around 145.972. Most of the time there is no beacon at all. Sometimes there is jibberish. Usually the signal is very weak.
With AO-7 going through eclipse on every orbit, the satellite can come out of eclipse in different modes/ options. Recently there have been times where the beacon has transmitted clear CW over North America, something I have not heard over the years.
According to the DK3WN website, there was some cw telemetry back in 2002 when the satellite was discovered to be working again. And there was some discussion about what is valid data based on the last 3 digits sent in the 24 group block of data. If the value is 649, 650, or 651, the data is likely valid.
I first heard the image of the cw signal around 958. It was so loud I thought it was a valid user at first. But since the cw was all numbers I tuned up to the beacon frequency and there the signal was louder than anything I have ever heard on AO-7. It took a while for me to get the recorder running but I managed to capture some data. After playing it back I found that there was only one block of data where the last group was valid, a 649. Other later transmissions were loud but the data was much different and the last group was not correct.
I couldn't locate a telemetry calculator at first so I decided to build one on Excel using the formulae provided by DK3WN. The data follows:
AO-7B Telemetry 24July2014 2318UTC POS Parameter Range Raw Real
1A Total Solar Array Current 0-3000ma 171 2094.5ma 1B +X Solar Panel Current 0-2000ma 193 110ma 1C -X Solar Panel Current 0-2000ma 157 830ma 1D +Y Solar Panel Current 0-2000ma 108 1810ma 2A -Y Solar Panel Current 0-2000ma 286 250ma 2B RF Power Out 70/2 0-8watts 204 7.3728W 2C 24 Hour Clock Time 0-1440min 201 15.16min 2D Batt Ch/Discharge Current-2000/+2000 207 -1720ma 3A Batt Voltage 6.5-16.4 361 12.7V 3B Half Batt Voltage 0-10v 397 9.7V 3C Batt Charge Reg #1 0-15v 340 6V 3D Batt Temperature -30 to +50C 300 95.8C 4A Baseplate Temperature -30 to +50C 446 27.72C 4B PA Temperature 2/10 -30 to +50C 401 94.32C 4C +X Face Temperature -30 to +50C 430 51.4C 4D +Z Face Temperature -30 to +50C 498 -49.24C 5A PA Temp 70/2 -30 to +50C 545 29.2C 5B PA Emitter Current 2/10 0-1167ma 502 92.84MA 5C Module Temp 70/2 -30 to +50C 543 32.16C 5D Inst. SW Regulator 0-93ma 527 33.14MA 6A RF Power Out 2/10 0-10,000mw 606 23.076MW 6B RF Power Out 435 0-1000mw 643 219.9MW 6C RF Power Out 2304 0-100mw 679 255.881MW 6D Midrange Telemetry Cal 0-.5v 649 0.49
There are some values which are obviously not correct. Some sensors might not be working properly since some values are out of range. However, the solar panel numbers might be somewhat correct. I wouldn't doubt it if the transmitter was putting out 7 watts at the time.
Perhaps there are those who are familiar with the AO-7 telemetry that can make some sense out of the data. Unfortunately we don't have multiple blocks of good data to compare readings. Maybe some have recorded recent CW data and can find some good blocks that can be shared here.
The data was copied on my Arizona remote and Skype was being used to listen. But I am fairly confident that the cw copied is correct.
73, John K8YSE
John,
The December 1974 issue of the AMSAT Newsletter covered AO-7 telemetry fairly in depth. Included was a description on reading the telemetry followed by a telemetry conversion table. You can find the issue in Phil Karn's archive http://www.ka9q.net/AMSAT-Newsletter-1974.pdf The article begins at about page 100 of the PDF
EMike
EMike McCardel, KC8YLD VP for Educational Relations AMSAT-NA
Sent from my iPhone
On Jul 31, 2014, at 2:26 PM, John Papay john@papays.com wrote:
It is very rare to hear clear CW from the AO-7B telemetry beacon around 145.972. Most of the time there is no beacon at all. Sometimes there is jibberish. Usually the signal is very weak.
With AO-7 going through eclipse on every orbit, the satellite can come out of eclipse in different modes/ options. Recently there have been times where the beacon has transmitted clear CW over North America, something I have not heard over the years.
According to the DK3WN website, there was some cw telemetry back in 2002 when the satellite was discovered to be working again. And there was some discussion about what is valid data based on the last 3 digits sent in the 24 group block of data. If the value is 649, 650, or 651, the data is likely valid.
I first heard the image of the cw signal around 958. It was so loud I thought it was a valid user at first. But since the cw was all numbers I tuned up to the beacon frequency and there the signal was louder than anything I have ever heard on AO-7. It took a while for me to get the recorder running but I managed to capture some data. After playing it back I found that there was only one block of data where the last group was valid, a 649. Other later transmissions were loud but the data was much different and the last group was not correct.
I couldn't locate a telemetry calculator at first so I decided to build one on Excel using the formulae provided by DK3WN. The data follows:
AO-7B Telemetry 24July2014 2318UTC POS Parameter Range Raw Real
1A Total Solar Array Current 0-3000ma 171 2094.5ma 1B +X Solar Panel Current 0-2000ma 193 110ma 1C -X Solar Panel Current 0-2000ma 157 830ma 1D +Y Solar Panel Current 0-2000ma 108 1810ma 2A -Y Solar Panel Current 0-2000ma 286 250ma 2B RF Power Out 70/2 0-8watts 204 7.3728W 2C 24 Hour Clock Time 0-1440min 201 15.16min 2D Batt Ch/Discharge Current-2000/+2000 207 -1720ma 3A Batt Voltage 6.5-16.4 361 12.7V 3B Half Batt Voltage 0-10v 397 9.7V 3C Batt Charge Reg #1 0-15v 340 6V 3D Batt Temperature -30 to +50C 300 95.8C 4A Baseplate Temperature -30 to +50C 446 27.72C 4B PA Temperature 2/10 -30 to +50C 401 94.32C 4C +X Face Temperature -30 to +50C 430 51.4C 4D +Z Face Temperature -30 to +50C 498 -49.24C 5A PA Temp 70/2 -30 to +50C 545 29.2C 5B PA Emitter Current 2/10 0-1167ma 502 92.84MA 5C Module Temp 70/2 -30 to +50C 543 32.16C 5D Inst. SW Regulator 0-93ma 527 33.14MA 6A RF Power Out 2/10 0-10,000mw 606 23.076MW 6B RF Power Out 435 0-1000mw 643 219.9MW 6C RF Power Out 2304 0-100mw 679 255.881MW 6D Midrange Telemetry Cal 0-.5v 649 0.49
There are some values which are obviously not correct. Some sensors might not be working properly since some values are out of range. However, the solar panel numbers might be somewhat correct. I wouldn't doubt it if the transmitter was putting out 7 watts at the time.
Perhaps there are those who are familiar with the AO-7 telemetry that can make some sense out of the data. Unfortunately we don't have multiple blocks of good data to compare readings. Maybe some have recorded recent CW data and can find some good blocks that can be shared here.
The data was copied on my Arizona remote and Skype was being used to listen. But I am fairly confident that the cw copied is correct.
73, John K8YSE
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participants (2)
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EMike McCardel -
John Papay