Thanks to everyone's previous work, I am receiving data packets from the Davis ISS using a Raspberry Pi, Node.js, and an AdaFruit RFM69 radio.
The problem is with the temperature (message 8 ). I have two Davis stations, one of them sends the temperature in the way Dekay describes (simply divide the received value by 160 to get the degrees F). The other station sends it in a format that I cannot decode. STRMON matches what I am receiving so I know the data is correct. The console displays the correct real temperatures from this format so it knows how to decode it.
The station that works as Dekay describes was purchased in 2009; the one with the strange values was purchased about 2004.
Here are a few samples to show the mystery message 8 values - the columns are hop index, packet bytes, freq, signal strength, millis since last packet, temperature bytes and console temp (x10 so 181 = 18.1F). As you can see the rcvd value decreases as the actual temp increases - specifically, the received value decreases by 0x40 for each 0.1 degree increase in actual temp (with a skip once in a while).
Has anyone seen this before? I have plenty more samples that I can post if needed.
Thank you,
Kevin
0 : 80 00 77 b5 c1 00 f7 12 ff ff -- 911413818 -72.0dBm -- 2606ms rcvd: b5c1, console: 180
24 : 80 00 77 b5 81 00 fa de ff ff -- 909406860 -71.0dBm -- 2508ms rcvd: b581, console: 181
48 : 80 00 77 b5 41 00 ec 8a ff ff -- 907901123 -66.0dBm -- 2605ms rcvd: b541, console: 183
21 : 80 00 77 b5 01 00 e1 46 ff ff -- 903385376 -73.0dBm -- 2606ms rcvd: b501, console: 184
2 : 80 00 77 b4 c1 00 c0 22 ff ff -- 911915161 -74.0dBm -- 2604ms rcvd: b4c1, console: 186
30 : 80 00 77 b4 81 00 cd ee ff ff -- 902884521 -70.5dBm -- 2508ms rcvd: b481, console: 188
7 : 80 00 77 b4 41 00 db ba ff ff -- 918438354 -70.0dBm -- 2503ms rcvd: b441, console: 189
31 : 80 00 77 b4 01 00 d6 76 ff ff -- 910912109 -67.0dBm -- 2605ms rcvd: b401, console: 191
8 : 80 00 77 b3 c1 00 45 b2 ff ff -- 908904663 -74.0dBm -- 2604ms rcvd: b3c1, console: 192
32 : 80 00 77 b3 81 00 48 7e ff ff -- 921949707 -72.5dBm -- 2504ms rcvd: b381, console: 194
9 : 80 00 77 b3 41 00 5e 2a ff ff -- 920445374 -74.5dBm -- 2508ms rcvd: b341, console: 195
41 : 80 00 77 b3 01 00 53 e6 ff ff -- 904389343 -69.5dBm -- 2612ms rcvd: b301, console: 197
18 : 80 00 77 b2 c1 00 72 82 ff ff -- 907399414 -66.5dBm -- 2503ms rcvd: b2c1, console: 199
46 : 80 00 77 b2 81 00 7f 4e ff ff -- 905391968 -69.0dBm -- 2504ms rcvd: b281, console: 200
23 : 80 00 77 b2 41 00 69 1a ff ff -- 923456299 -78.0dBm -- 2604ms rcvd: b241, console: 202
4 : 80 00 77 b2 01 00 64 d6 ff ff -- 914926575 -73.5dBm -- 2604ms rcvd: b201, console: 203
36 : 80 00 77 b1 c1 00 2b d2 ff ff -- 927469849 -75.0dBm -- 2505ms rcvd: b1c1, console: 205
17 : 80 00 77 b1 81 00 26 1e ff ff -- 921448364 -71.0dBm -- 2505ms rcvd: b181, console: 206