ANS 321 AMSAT NEWS SERVICE SPECIAL BULLETIN - AO-85 Commissioned, Handed Over To AMSAT-NA Operations
AMSAT NEWS SERVICE SPECIAL BULLETIN ANS-321
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* AO-85 Commissioned, Handed Over To AMSAT-NA Operations
SB SAT @ AMSAT $ANS-321.01 ANS-321 AMSAT News Service Weekly Bulletins
AMSAT News Service Bulletin 321.01
From AMSAT HQ KENSINGTON, MD.
November 17, 2015 To All RADIO AMATEURS BID: $ANS-321.01
AO-85 Commissioned, Handed Over To AMSAT-NA Operations
AO-85 has been formally commissioned and turned over to AMSAT Operations, who are now responsible for the scheduling and modes.
The following guidelines are provided for users:
Uplink power should be on the order of minimum 200 W EIRP for full quieting at lower antenna elevation angles. Your mileage may vary. With an Arrow, 5 W has been used successfully to make contacts.
Polarity is important. The satellite antennas are linear. So, if you are using linearly polarized antennas, you will need to adjust throughout the pass. Full duplex operation facilitates these adjustments while transmitting and is highly recommended.
The downlink is very strong and should be heard well with almost any antenna.
Downlink audio is 5 kHz deviation, as expected. Many will perceive that the audio is "low." This is an effect of the filtering below 300 Hz, which provides for the DUV telemetry, coupled with any noise on the uplink signal resulting from lack of full quieting or being off frequency. That makes for less fidelity than a typical receiver in terms of audio frequencies passed.
Transmit (downlink) frequency varies with temperature. Due to the wide range of temperatures we are seeing in the eclipse cycle, the transmitter can be anywhere from around 500 Hz low at 10°C to near 2 kHz low at 40°C.
Receive frequency has been generally agreed to be about 435.170 MHz, although the AFC makes that hard to pin down and also helps with the uplinks that are off frequency.
Probably the most notable observations about AO-85 are an apparent lack of sensitivity and difficulty in turning on the repeater with the 67 Hz CTCSS when it is not yet activated, or holding it on by the presence of the CTCSS. We have determined a probable cause for the sensitivity issue and while that can't be fixed on AO-85 we are taking steps to prevent similar issues on the rest of the Fox-1 CubeSats. The tone detection threshold along with the receive sensitivity issue makes it hard to bring up the repeater. This is being addressed by adjusting the values for a valid tone detection in the other Fox-1 CubeSats now that we have on orbit information about temperatures and power budget. Full details will be in the Nov/Dec AMSAT Journal.
It is important to remember that science is the reason behind the Fox-1 satellites. Not only does science help with the launch cost, it provides a great amount of educational value both from the science payload and in amateur radio itself. The data-under-voice (DUV) telemetry is an excellent way to provide the science without sacrificing the use of the satellite for communications, which would be the case if higher speed downlinks were needed. DUV provides constant science as long as the repeater is in use, which in turn provides more downlink data for the science - a mutually beneficial combination.
Fox-1A is AMSAT-NA's first CubeSat. Many new techniques are incorporated and lessons will be learned, as with any new "product." The Fox-1 Project is a series of CubeSats. A total of five will be built and flown. Launches are scheduled for three more, and a new NASA CubeSat Launch Initiative proposal will be submitted for the fifth. We will incorporate changes from what we learn in each launch, to the extent possible, in subsequent Fox-1 CubeSats.
Of the four NASA sponsored CubeSats on the ELaNa XII launch October 8, we are sad to report that ARC1 was never heard from and BisonSat was lost after a few weeks of operation. AMSAT extends our deepest sympathy to the people who worked so hard on these projects. To our members, we want to say that the Fox Team is very proud and pleased that our first CubeSat is very successful and hopefully will be for some time.
[ANS thanks Jerry NoJY for the above information]
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73, This week's ANS Editor, EMike McCardel, KC8YLD kc8yld at amsat dot org
AMSAT NEWS SERVICE SPECIAL BULLETIN ANS-321
Downlink audio is 5 kHz deviation, as expected. Many will perceive that the audio is "low." This is an effect of the filtering below 300 Hz, which provides for the DUV telemetry, coupled with any noise on the uplink signal resulting from lack of full quieting or being off frequency. That makes for less fidelity than a typical receiver in terms of audio frequencies passed.
[...]
It is important to remember that science is the reason behind the Fox-1 satellites. Not only does science help with the launch cost, it provides a great amount of educational value both from the science payload and in amateur radio itself. The data-under-voice (DUV) telemetry is an excellent way to provide the science without sacrificing the use of the satellite for communications, which would be the case if higher speed downlinks were needed. DUV provides constant science as long as the repeater is in use, which in turn provides more downlink data for the science - a mutually beneficial combination.
I designed the DUV telemetry system on Fox-1, with an important suggestion (use 8b10b coding for spectral shaping) from Tony, AA2TX. It's important to remember the severe design compromises imposed by the requirement that the satellite itself be an analog FM repeater, confining the telemetry to modulating frequencies below 300 Hz.
These design compromises would have been unnecessary with a fully digital communications payload, like those on every non-amateur satellite launched in at least the past decade or two. I've made it clear that this is my last telemetry design for an analog spacecraft. It's past time for AMSAT to move into the all-digital era.
--Phil, KA9Q
Phil, I don't dispute your expertise in this opinion -- you're right when you say:
It's past time for AMSAT to move into the all-digital era.
But, the appeal of using a pair of HTs or other simple radios with an Arrow sure is strong -- especially for truly neophyte operators.
What would replace this entry level equipment? A laptop and an Arduino and a radio?
Really curious what you think; I expect you have a very learned opinion.
-- bag
Bryan KL7CN/W6
On Nov 18, 2015, at 15:28, Phil Karn [email protected] wrote:
AMSAT NEWS SERVICE SPECIAL BULLETIN ANS-321
Downlink audio is 5 kHz deviation, as expected. Many will perceive that the audio is "low." This is an effect of the filtering below 300 Hz, which provides for the DUV telemetry, coupled with any noise on the uplink signal resulting from lack of full quieting or being off frequency. That makes for less fidelity than a typical receiver in terms of audio frequencies passed.
[...]
It is important to remember that science is the reason behind the Fox-1 satellites. Not only does science help with the launch cost, it provides a great amount of educational value both from the science payload and in amateur radio itself. The data-under-voice (DUV) telemetry is an excellent way to provide the science without sacrificing the use of the satellite for communications, which would be the case if higher speed downlinks were needed. DUV provides constant science as long as the repeater is in use, which in turn provides more downlink data for the science - a mutually beneficial combination.
I designed the DUV telemetry system on Fox-1, with an important suggestion (use 8b10b coding for spectral shaping) from Tony, AA2TX. It's important to remember the severe design compromises imposed by the requirement that the satellite itself be an analog FM repeater, confining the telemetry to modulating frequencies below 300 Hz.
These design compromises would have been unnecessary with a fully digital communications payload, like those on every non-amateur satellite launched in at least the past decade or two. I've made it clear that this is my last telemetry design for an analog spacecraft. It's past time for AMSAT to move into the all-digital era.
--Phil, KA9Q _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
El 18/11/15 a las 23:28, Phil Karn escribió:
I designed the DUV telemetry system on Fox-1, with an important suggestion (use 8b10b coding for spectral shaping) from Tony, AA2TX. It's important to remember the severe design compromises imposed by the requirement that the satellite itself be an analog FM repeater, confining the telemetry to modulating frequencies below 300 Hz.
These design compromises would have been unnecessary with a fully digital communications payload, like those on every non-amateur satellite launched in at least the past decade or two. I've made it clear that this is my last telemetry design for an analog spacecraft. It's past time for AMSAT to move into the all-digital era.
Dear Phil,
I'm wondering if it would be reasonable for future satellites to use an SDR transmitter, to allow to use an analog FM downlink and digital telemetry on two different frequencies (spaced about 20KHz apart or so). As others have said, analog FM is quite desirable because it allows for a very simple groundstation. Also, the current state of amateur digital voice is not so stable with all these competing standards that have closed implementations or use patented codecs.
73,
Dani M0HXM/EA4GPZ.
participants (4)
-
Bryan KL7CN -
Daniel Estévez -
E.Mike McCardel -
Phil Karn