Архив за 01.11.2017

Всем привет. Кто собирал по этой схеме конвертер?…

Всем привет. Кто собирал по этой схеме конвертер?

Comment on Outernet Dreamcatcher Sale is a Steal: $39 USD RTL-SDR + Computing Board All-In-One by Tehrasha

Which is still cheaper than the lowest price it was available for before, without shipping.

No ADS-B reception with LNA — overloaded receiver, LNA not working or something else?

Hello all.

I have few questions regarding my new RTLSDR setup not working good with LNA.

Current setup:

  • RTL-SDR v3
  • Collinear antenna mounted on top of the building above almost all obstacles (few trees in same height 50 meters distant)
  • 10 meters of RG59 cable with N and SMA connector
  • LNA4ALL with Bias-T connected to receiver
  • Raspberry PI 3 with 5.3V 2A power source
  • ADS-B Receiver with dump1090-mutability

I have problem with receiving ADS-B when LNA is connected.

  1. Without LNA I get up to 250 messages per second with 189nm maximum range (information from planefinder).

  2. After connecting LNA and turning on Bias-T I get 0 messages/sec.

  3. After changing gain from "max" to "agc" i get up to 5 messages/sec with reduced range.

I'm wondering if my receiver is overloaded, LNA not working properly or something else beside?

Possible interference sources:

  • I have 3 cell phone towers distant 0.8km, 1.34km, 1.43km with maximum ERP 30 dbw

  • I have LOS of two TV stations. One distant 25km and emiting 120kw radio and 110kw television. Television is between 500mhz and 750mhz. Other TV station is 8.5 km, emitting power not known.

  • Antenna is mounted on steel post 2 meters above roof, with 2 TV antennas mounted below.

  • 30 meters distant 5ghz private wifi access point, but antenna is directional not in my position.

This is all possible interference that I know.

I made few rtl_power tests to see is there any interference nearby.

Next are pictures of rtl_power.

  1. RTL-SDR without LNA, 800-1200mhz, gain 30 https://i.imgur.com/pZMmnju.png
  2. RTL-SDR without LNA, 500-750mhz, gain 30 https://i.imgur.com/hQkNKUc.png
  3. RTL-SDR without LNA, 80-110mhz, gain 30 https://imgur.com/Jt78OFQ.png
  4. RTL-SDR with LNA Bias-T, 800-1200mhz, gain 30 https://i.imgur.com/Uti835i.png
  5. RTL-SDR with LNA Bias-T, 800-1200mhz, gain 0.9 https://i.imgur.com/ksnZE5c.png

As you can see, lots of noise when LNA is activated. Is it because antenna position and interference or possibly malfunction LNA?

Do I need to invest in filter? Or I don't need LNA at all? Is there problem with gain settings?

If I need filter, is this good to make for start?



Other data that I can supply is dump1090 performance graphs without LNA.


Any help is more then welcome. I can measure more things, provide more information or pictures.

submitted by /u/sipe1
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User Projects • retrieving RSSI values in software

Hello I am new to the SDR-LTR community and was hoping to find some answers here. I'm not at all a DIY in the electronic field, yet I am majoring in it. So bear with me if I will mention some idiotic things :? :? :?

I was wondering what would be the best way to fetch the RSSI values of signals acquired during measurements. I would like to come up with some kind of classification algorithm of protocols based on RSSI values. I am planning on buying the SDR-LTR (USB) and know that it is compatible with SDR#. Is it possible to get the RSSI values in the software in an easy way or can I only reach them on hardware level.



Statistics: Posted by BSJR — Wed Nov 01, 2017 7:08 pm

Troubleshooting Help • Re: No sound on FM

Found out how to do the screenshot.

Details below
Screenshot (3).png

Statistics: Posted by rifleman49 — Wed Nov 01, 2017 6:29 pm

The culprit is the lna I broke

Now, I need to re-adjust my helical bandpass filter since I've been tuning it for fm stations and noaa radio - https://imgur.com/a/rK4no
However, does the noise pattern reminds you of something? It does for me. Previously I had a v-dipole antenna installed/mounted at the very same place where the new QFH is at right now. The noise is very similar. So looks like my house on the east side of it and the honeylocust tree on the southwest side of it is causing this signal lost. I'm still wondering since the qfh antenna is about 5 ft higher from my previous v-dipole. Anyways, I haven't tuned the bandpass filter yet. We'll find out later. Oh, I'm also going to buy another lna.

submitted by /u/Oxffff0000
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Troubleshooting Help • sdr rtl wirelles

hi, I would like to know how best to receive data from my dongle, for wirelles, the issue is that the antenna is too far away, and I did not want to lose antenna signal. the dongle will get to receive the inmarsat.

ola , gostaria de saber qual a melhor forma de poder receber os dados do meu dongle , por wirelles, a questao é que a antenna esta muito afastada, e nao queria perder sinal da antenna . o dongle vai ficar a receber o inmarsat.

translated with google translater


Statistics: Posted by Ct1etx — Wed Nov 01, 2017 5:51 pm

Comment on Outernet Dreamcatcher Setup with ADS-B dump1090 and PiAware Tutorial by thebaldgeek

I run a fleet of Pi ADSB receivers over Southern California, any comment on how this thing actually performs?
Its price point is attractive since you don’t have to buy the USB dongle, but if it is rather deaf, then its a bad buy.

Comment on Outernet Dreamcatcher Sale is a Steal: $39 USD RTL-SDR + Computing Board All-In-One by Max

If it looks too good to be true it’s probably too good to be true
$54.83 with shipping, plus customs duty

Comment on Testing the Outernet Dreamcatcher: Linux Based ARM PC with Built in RTL-SDR by Bertie

Strange I’d take a totally different reading looking at the same information. That they may have made more than they should (overestimated market size), are stuck paying storage, security and insurance costs on a rapidly depreciating item. So they are cutting hard and selling at almost cost (or below) to prevent further haemorrhaging. I’d see it as getting a great deal on what looks like extremely well designed hardware and throwing a lifeline to a small company.

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