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Author Topic: APRS question..  (Read 16020 times)

Posts: 31

« on: October 10, 2017, 05:11:50 PM »

         Just getting my feet wet with APRS. On the Yaesu website the FTM-400xdr there is no information if this unit has digipeat capabilities? Where as the Kenwood 710G Series has a full functionality tnc and digipeat options.
How important is the digipeat on APRS or is there other options within the FTM-400xdr menus that compensate?
Thanks in advance.

Posts: 7

« Reply #1 on: October 14, 2017, 11:12:09 PM »

If you are just starting out you should not need to digipeat and depending on your QTH can cause problems. That being said what are your goals with APRS.

Posts: 22

« Reply #2 on: October 15, 2017, 04:31:20 PM »

As I understand it the Yaesu radio does NOT digipeat.
Why would you need this? If you want to take a hike into a remote area with your HT it may not have enough power/ antenna to make it to an APRS digi or I-gate. If you set up your mobile rig in your car at the trail head as a digipeater then you can hit it with you HT and then go back out to a node somewhere in the larger system.
I don't know why Yaesu didn't include this feature.
It is possible to simply set up your mobile rig as a standard cross-band repeater with the 2m side on 144.390 and the UHF side on 445.925 (a UHF APRS frequency suggested by Bob himself). You can then repeat your HT's packets thru your mobile rig and out to the APRS network.

Posts: 105


« Reply #3 on: October 20, 2017, 10:43:05 AM »

Perhaps it's best if you start by taking a basic look at what digipeating is. It's essentially a "store-and-forward" like system. You transmit an APRS packet, the receiver at the digipeter decodes this packet; looks at the PATH information; modifies this (if it's configured properly) to indicate it's been repeated; then transmits it back over the APRS frequency. It's the same idea as a repeater; you use a good location with LOS to a wide area.

Do you really need this feature? Most users do not. There are likely already existing digipeters in your area providing this service; adding another one can in fact cause problems. It's like I don't bother adding a digipeter because I am 3 miles from an existing one. All mine would do is be bouncing and repeating packets from the existing one. That is also one thing one needs to consider; the digipeaters operate on the same frequency and any other digipeter that hears it will also repeat the packet if the number of hops specified in the PATH haven't been all used up.

While KD4UPL was on the right path (har-har); the problem I find with his method is that I don't believe there is a lot of activity on the UHF APRS frequency, at least in my even if you merely cross-band repeated the FM signal, is there anything out there that does it? Crossbanding UHF to VHF would be a suitable alternative, but then you run the risk of your UHF signal not making it to your radio with however deep in the woods you are.

Again, I echo KI4UTU's question; what are your goals with APRS? What are you going to be using it for? What cases would you need your own digipeter or do you "just want the feature". You can always make your rig a digipeter with a TNC and a PC, but that might be a little much if you have a real need for a portable setup to ensure your packets hit the APRS-IS system.

Posts: 105

« Reply #4 on: October 25, 2017, 09:00:08 AM »

For a digipeater, your ht would have to be pinging out aprs to your mobile in the car. I assume the op does not have one since they are not asking about it. Is this correct op?
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