[K6BW] Fw: Terminal Node Controllers

[Jay Hubert]

Bill,

Thanks for the phone discussion today.  I looked at the APRS link you provided below. While APRS definitely requires a good TNC, I am not sure that high baud is really an issue for many APRS operations (although some do operate at 9600 baud).

Look at http://www.kc2rlm.info/soundcardpacket/6modes.htm  The box at the top of the page indicates that the sampling rate of most sound cards limits their data throughput to a maximum standard baud of about 19.2 k. This site seems to have a useful discussion of what it takes to operate at 9600 baud.  Interestingly, some of the links point back to Steve Waterman whom you mention in your note.  Other links point to some East Bay users. However, the kc2rlm site is very much committed to and supportive of AGWPE software. While AGWPE may be the best solution, I would like to have that confirmed somewhere else.  One of the other comments at the bottom of the page indicates that at 9600 baud, 10 W transmit power, and with a good antenna, one might expect a range of about 10 miles.  Marin's geography might limit range more than that in some places.

I have attached the CFR part 97 rules that clarify packet transmission speeds.  In summary:

Band                baud    bandwidth kHz
Below 10 m           300          1
10 m                1200          1
6m, 2m             19.6k         20
1.25 m, 70 cm        56k        100
33 cm and above   no limit   no limit

Part 97.309 also clarifies that unencrypted digital protocols are acceptable, provided that the "technical characteristics have been documented publicly...for the purpose of facilitating communication."

I appreciate your comment about the 802.11g standard for wireless networking.  The standard uses spread spectrum transmission at 2400 GHz. The standard channels fall entirely within the 13 cm amateur band. As near as I can tell, unlicensed users of the 802.11g transmitters are restricted to 250 mW. The power limitation does not seem to apply to FCC licensed amateurs. Of course, there could be interference issues because there are many other users in this band.  However, it seems to me the implementation of 802.11g at higher power would really be home brew.  Is anyone doing that?

I met a guy in West Marin who has a T1 line that he parcels out to subscribers who link up to him via radio. I can't imagine that 250 mW is enough to reach his distant subscribers. I wonder what they are using and what kind of data rates they get.

Let me know what you think.

Jay
415.457.3914


----- Original Message ----- 
From: Bill Smith 
To: jayhubert at comcast.net 
Sent: Wednesday, October 28, 2009 8:39 AM
Subject: Re: [K6BW] Terminal Node Controllers


Hi Jay,
 
An APRS website has a list of equipment which might be useful for you to review. 
 
http://info.aprs.net/index.php?title=Hardware
 
I was speaking with Steve Waterman K4CJX a Winlink 2000 expert last night and he strongly recommends 9600 baud packet.  He mentioned all the current radio models support 9600 baud (it used to be a real project to tap into the discriminator and modulator circuits to tease a radio into 9600 baud operation).  He did mention a MFJ KISS-mode only TNC (didn't mention the model) as an inexpensive modem option.  MFJ equipment carries a "reputation" so would look carefully in that direction before taking any steps.
 
I am really not familiar with current TNC products, especially concerning 9600 baud operation.  A HF (short-wave frequencies) Winlink 2000 RMS node has just been installed at Hamilton and once it settles down we will be turning our attention toward installing a VHF RMS node.  As mentioned, Steve strongly suggested use of 9600 baud with Winlink and from what I can see of throughput, would very much agree.  Just what equipment will be needed to support the VHF node is yet to be determined.
 
I'll try to reach you by telephone to discuss further.  Or, if you have a chance, give me a call.
 
Bill
415-456-4481
 
  ----- Original Message ----- 
  From: Jay Hubert 
  To: k6bw at mailman.qth.net 
  Sent: Wednesday, October 28, 2009 10:02 AM
  Subject: [K6BW] Terminal Node Controllers


  I would like some local input on selecting a terminal node controller to use primarily for emergency packet communication.  I expect to use a laptop (netbook) with a dual band mobile transceiver (Kenwood TMV71E, 144/440 MHz).  I want to be able to connect to local WinLink nodes.

  I realize there are lots of choices, but cost, size, and the need for 110 ac power work against the most powerful and flexible TNCs from Kantronics, Timeware, RIGblaster, and Pactor.  They also seem to be overkill for my primary EmComm application. That seems to narrow the choices down to the RIGblaster Plug and Play, SignaLink USB (contains its own sound card), and AGWPE Pro (software only).  Roughly speaking, these are all $100 solutions.

  Am I on the right track? What is your experience? What packet modes are most likely to be used locally? Does anyone have a specific recommendation?

  73 de K0OLK
  Jay