so ive been running APRS for about a year now mostly just tracking my car and occasionally sending messages to a buddy across town who also runs it. setup is a kenwood TM-D710G into a decent vertical on the roof, nothing fancy. the problem is there's this dead zone about 15 miles southeast of me where packets just disappear. i can watch the path on aprs.fi and it'll show my beacon hitting the digipeater on the ridge just fine but then when i drive into that valley it's like i stop existing on the network.

i've tried bumping up my transmit power and messing with the WIDE1-1,WIDE2-1 path settings but honestly i'm not even sure if that's the right approach or if im just causing more QRM on the frequency. thought about setting up a fill-in digi at my house since i'm on a hill but i dont really know if that would even reach into that valley or just create a mess. anyone dealt with something like this before, like is there a good way to figure out where the actual coverage holes are before just throwing hardware at it?

yeah that valley problem is real and pretty common honestly. the WIDE1-1 part of your path is specifically meant for fill-in digis so if you put one up on a hill with line of sight into the valley that should help a lot. before doing anything though i'd pull up the RF range analysis on aprsdirect.com or just look at what stations are hearing you on aprs.fi — there's a heard-by tab or something like that which shows you which digis are actually picking up your packets and from where.

the other thing is your beacon rate matters. if youre only beaconing every few minutes and driving through a marginal coverage area you might just be between beacons when youre in the good spot and then back in the hole by the time it fires again. smartbeaconing helps a lot with this if your radio supports it, the D710 definitely does so worth checking if you have that configured. i run mine pretty aggressive on the cornering settings because i do a lot of twisty roads.

fill-in digi is probably the right call but just make sure you configure it as WIDE1-1 only and not a full WIDE2 digi or you'll cause all kinds of duplicate packet problems downstream. seen that happen a few times where someone stands up a digi with too broad a path config and suddenly aprs.fi is showing 6 copies of every packet in a 50 mile radius. the guys running the regional APRS network in your area might also have coverage maps or be planning something already, worth reaching out to them before you go DIY on it.