I have installed a PiAware (Dump1090-Mutibility) with the Flight Aware ProStick / 1090MHz Band-pass Filter / 1090MHz ADS-B Antenna - 66cm / 26in. The antenna is connected to the filter via an eight meter TrendNet Reverse SMA to N-Type cable (TEW-L208) (50 Ohm connector). Filter & ProStick are connected directly.
The performance isn’t what I expect - although some statistics are somewhat better than the NooElec + cheap-o antenna it replaced, overall signal strength is low, few aircraft are captured and the maximum distance is somewhere around 50 nm.
The FA system is mounted on a pole 15’ AGL; the NooElec system was sitting on a tin can on a first floor window.
The system is located only 10 miles W of KDFW, so I would expect to see hundreds of aircraft for hundreds of miles, not the fewer than 20 very close aircraft I currently see.
I have assumed the cable is the problem and have a simple N to SMA connector arriving tomorrow so I can test that theory. However, I have a few questions:
- If it is the cable, what cable do I need? It needs to be at least 25 feet so I can get it up the pole.
- Could it be something else? If so, what?
Here are stats and graphs & thanks for your help:
Is the small number of accepted packets typical?
Statistics: Wed Jun 29 21:17:04 2016 UTC - Wed Jun 29 22:17:04 2016 UTC Local receiver: 4012769280 samples processed 0 samples dropped 0 Mode A/C messages received 22188865 Mode-S message preambles received 13565084 with bad message format or invalid CRC 8612389 with unrecognized ICAO address 10837 accepted with correct CRC 555 accepted with 1-bit error repaired -35.4 dBFS noise power -22.6 dBFS mean signal power -9.5 dBFS peak signal power 0 messages with signal power above -3dBFS Messages from network clients: 0 Mode A/C messages received 495 Mode S messages received 0 with bad message format or invalid CRC 0 with unrecognized ICAO address 495 accepted with correct CRC 0 accepted with 1-bit error repaired 11887 total usable messages 6 surface position messages received 786 airborne position messages received 691 global CPR attempts with valid positions 0 global CPR attempts with bad data 0 global CPR attempts that failed the range check 0 global CPR attempts that failed the speed check 0 global CPR attempts with insufficient data 87 local CPR attempts with valid positions 67 aircraft-relative positions 20 receiver-relative positions 14 local CPR attempts that did not produce useful positions 8 local CPR attempts that failed the range check 0 local CPR attempts that failed the speed check 0 CPR messages that look like transponder failures filtered 4657 non-ES altitude messages from ES-equipped aircraft ignored 83 unique aircraft tracks 40 aircraft tracks where only one message was seen 0 HTTP requests CPU load: 9.0% 227688 ms for demodulation 88868 ms for reading from USB 6853 ms for network input and background tasks
You can see where the antenna / modulator systems were replaced around 24z on Tuesday. Signal strength drops, more single packets are picked up , but overall aircraft tracked remained the same or dropped.