I’ll have a go at answering (some of) your questions :-) See inline below.
Kieran > On 13 Apr 2017, at 15:22, Scott Myers <[email protected]> wrote: > > Thanks Tim for the reply and thanks for the links. I've read all those links > before. I think I have read nearly everything there is to read, including > development history and the manual. Granted, I could have missed or skimmed > over the details I am looking for. BTW- I'm a 55 year old mechanical > engineer and an Amateur Extra class, AC8DE. > > My first question is on the uplink/downlink frequencies. It simply states > 433 MHz. I assume this to be an approximate frequency in the 70 cm band and > not the actual exact frequencies. >> Correct, it’s the 70cm band. There are 9 ‘preset’ frequencies and you can >> change the frequencies if you need to. The hardware is capable of quite a >> wide range - look up the TI CC1200 radio chip. > Rarely is something right at 433.000 MHz. Are there separate uplink and > downlink frequencies (full duplex) or does it switch on/off transmit/receive > at each transceiver (Telmetrum and Teledongle) using the same exact > frequency. >> It’s single frequency. The Telemetrum (or Telemega and others) will run in >> one of two modes. Idle (Pad) mode - the telemetrum waits for a query from >> the ground station (teledongle, telebt) and then responds with the packet(s) >> that have been requested. Flight mode - the telemetrum stops listening and >> just spews (technical term) packets of data. > Is the frequency(ies) movable in case of frequency conflict and RFI? >> Yes, by default 9 different frequencies (channels). > How wide is the data bandwidth in KHz? >> Can’t remember off the top of my head. See the manual which lists the >> frequencies. > I happen to have a commercial radio (HBC Radiomatic) in my launch system > design that uses, yep... the 433 frequency range. I can select 4 discrete > "channels" on it to help it avoid any conflict, but it would be good to know > where the Telemetrum actually transmits and receives so I can shift the > launcher away from that frequency as far as possible. >> Yeah, shouldn’t be a problem. > Then there is the case of what if there is another Telemetrum or two around > the launch site; a very probably scenario. (I think they are all coded and > using "telegraph" messaging handshaking to avoid conflict with another > Telemetrum, but I could be wrong.) >> They are each on their own frequency - nothing fancy and no attempt to avoid >> trampling over someone else’s frequency. This has to be managed at the >> launch site. > I could figure most of this out with a spectrum analyzer, but I'd have to buy > it first and then spend the time to test. Better to know these technical > details before I buy. >> It’s very simple, so no spectrum analyser required. The ground station >> software has a ‘scan’ operation where you can look for other users. However, >> launch site management of frequencies would be more reliable. > > I see there is a starter "kit" that uses the Teledongle. But there is also > the TeleBT, which seems to do everything the Teledongle does, PLUS adds > bluetooth for use with the Android App. It seems that starting with the > TeleBT would the better choice and don't even buy the Teledongle, but I > wanted to make sure I wasn't missing something on this. >> TeleBT seem good if that’s the way you want to go. Easier than the aerial >> being tethered to the groundstation laptop/tablet. I have only used the >> Teledongles though. The ‘kit’ also has a battery - remember to order one or >> two of those. > > I saw the history on older versions with the problems with pyro events and > battery rail sag and that it is supposed to be solved now. (An age-old > problem on many avionics packages.) I think I'd rather put a second LiPo on > the Telemetrum and give the pyro events their own rail and simply avoid any > potential rail sag issue. Just a small LiPo should do the job. I'm guessing > others have done this and I read where that is an option on the board. I'd > like feedback on that. >> That is an option, you can add a second LiPo if you want. Not had any issues >> so far with a single LiPo though. > > I read where there is an SMA connector option for the Telemetrum. >> There are pads to solder your own SMA connector if you want to. Other >> alternatives might be to solder a pigtail direct to the board to try to >> reduce component mass (they may go AWOL under acceleration :-)) > I've considered ordering the Telemetrum with that option and make the > antennas a permanent part of the Avionics bays fed with a short piece of > RG-316 or the like. Of course downside is mass of the connector soldered to > the board and having to support the feed line to account for high-G > conditions so the connector isn't broken from the board. I'd like some > feedback and discussion on the use of the SMA connector. I can't figure out > how to order the Telemetrum with that option anyway. >> Contact BDale for special order? Very easy to solder on your own in the >> field though (well at home before you go to the field…). > Perhaps it is a field mod? > > Thanks, > Scotty > > From: altusmetrum [mailto:[email protected]] On Behalf Of Tim > Cubbedge > Sent: Thursday, April 13, 2017 8:53 AM > To: 'Altus Metrum' > Subject: Re: [altusmetrum] New Member > > Have you looked here? > > http://altusmetrum.org/AltOS/doc/altusmetrum.html > <http://altusmetrum.org/AltOS/doc/altusmetrum.html> > > or here? > > http://altusmetrum.org/TeleMetrum/ <http://altusmetrum.org/TeleMetrum/> > > What do you want to know? > <> > From: altusmetrum [mailto:[email protected] > <mailto:[email protected]>] On Behalf Of Scott Myers > Sent: Thursday, April 13, 2017 7:11 AM > To: [email protected] <mailto:[email protected]> > Subject: [altusmetrum] New Member > > I just joined this Altus Metrum mailing list. I'm trying to get a bit more > information and learn more about the Telemetrum before I purchase one. > > Thanks, > Scotty > _______________________________________________ > altusmetrum mailing list > [email protected] > http://lists.gag.com/mailman/listinfo/altusmetrum
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