AO-51 packets statement
● (No.595) AO-51 packets statement (2008年8月11日) -------------------------------------------------- Subject: [amsat-bb] Re: ref my copy of ao-51 From: Douglas Quagliana Date: Sun, 10 Aug 2008 18:31:51 -0500 These are all packets sent from the onboard computer aboard AO-51. The PECHO-11 callsign is AO-51's broadcast callsign and the packets from this callsign (and PECHO-12) will contain data in the Pacsat Protocol format. This is the protocol that the onboard BBS uses to send and receive data in a way that time shares the satellite with all of the groundstations. Your computer needs to be running a program like WiSP in order for your computer to talk to the satellite using the Pacsat protocol. (I say "like WiSP" because there are other program besides just WiSP that also speak this protocol, but WiSP is probably the most popular.) The TLMS and TLMI packets are telemetry packets that contain information about the health and current status of the spacecraft. The TLMI packet is sent as binary data and you need a telemetry program like TlmEcho or Sabins to decode the telemetry into meaningful values. (Full disclosure: I wrote the Sabins telemetry program. It's free if you want a copy and I don't make any money from it.) If you received the 9600 baud signal with a program like Willow, or if you saved the received packets to a KISS file then Sabins can go back and show you the decoded telemetry and what it means. Since the data in the TLMI packets is binary you have to have saved it as a KISS file, not as ASCII text, or you will lose the binary data. If you use an Apple, then you need MacEchoTelem. > PECHO-11*>PBLIST <UI>: PB: Empty. > The queue is empty. Probably nobody is using the BBS right now. > PACBLS-8*>PACBLS-8 <UI>: PACBLS S Meter = 0 > The S Meter reads zero right now (or at the moment when the computer looked at the S meter). > PACB-1*>TLMI-1 <UI>: [and some binary data] > A telemetry packet. The binary data you put in your email didn't make it through the mailing list, but this packet will tell you all about the voltages, currents, and temperatures on each part of the spacecraft. Everything from the solar panels to the battery control regulators to the radios to the torque rod... and so on. It will also tell you what is turned on and what is turned off. You need tlmEcho or Sabins or MacEchoTelem to decode this information so that you can see what this packet is saying about the spacecraft. (Ok, you *could* do all of the polynomial calculations by hand, but it would be very tedious.) > PACB-1*>TLMS-1 <UI>: C0:0D C1:44 C2:76 C3:2F C4:04 C5:01 > A simpler telemetry packet. The "C" numbers are channel numbers and the hexadecimal number after the colon is a bitmask that tells you about things like the BCR DAC chip, the transmitters, the torque rod commands, receiver channels selected, CTCSS tones, some stuff about S band, and so on. For example, C2:76 tells you that - The RS-232 power monitor is OFF. - CTCSS TXA and TXB do not have valid tone(s). - Receivers 1 2 and 3 have their receive frequencies set to the main frequency. > PECHO-12*>BBSTAT <UI>: Open ABCD: > Again, more of "nobody is using the BBS right now." > PECHO-11*>STATUS <UI>: B: 120900539 > This is a byte counter. Your software can save this number and then when you get the next STATUS packet the software can look at the new number and get a count of the bytes (of certain types) that were sent by the spacecraft between the two packets. You can compare that count to the number (of those types) of bytes you received and see just how much of the satellite's transmitted data you missed or received in error. This gives you an idea of how good your reception of the satellite's signal was between those two packets. This number (apparently) does not increase for the bytes in telemetry packets. >PACB-1*>LSTAT <UI>: I P:0x13A8 o:0 l:27208 f:27245, d:1 st:6 e:8b > Some lower level satellite status. For example, "d:1" indicates that the AX.25 digipeater is enabled. If you were to send a packet "VIA" AO-51, and if AO-51 heard it without any errors, then AO-51 would retransmit your packet on the downlink for everyone else to receive it. For more information on the PASCAT protocols, see http://www.amsat.org/amsat/sats/nk6k/msatpro.html (Note: there are some addendums to those documents.) For more information specifically on AO-51, I recommend "AO-51 Development, Operation and Specifications" by Gould Smith. You should be able to get a copy if you call Martha at AMSAT or via the AMSAT store at http://www.amsat-na.com/store/item.php?id=100047 And if you're really really interested in this sort of stuff, you can get a copy of the "Digital Disk" which includes WiSP. (Full disclosure again: I wrote a few things on the Digital Disk, but again, I don't make money from it.) Good luck, and see you on the birds. 73, Douglas KA2UPW/5
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