Tuesday, November 22, 2016

Verizon 1x Voice/SMS 24-hour Traffic Waterfall

My last long-term waterfall post was about the double CDMA2000 signal near my house. After more reading, I'm convinced that it's 3G EV-DO (data only). The voice and texting signal is completely different. In that last post I thought the signal carried voice and texting and was surprised to see the activity pick up late at night, but someone told me that it must be phone updates, which would make sense for 3G data. Yesterday I started a 24-hour waterfall of the CDMA 1x signal near my house.

I wanted to know which network I was receiving, so I checked both Verizon and Sprint coverage in my city. Verizon covers the whole area while the nearest Sprint service is 7 miles away and the next closest coverage zone is 20 miles away. Guessing based on the incredible Verizon signal strength reported by an old flip phone, this signal must be Verizon.

Just like last time, I disabled Tuner AGC so we could see the tower's dynamic power changes. I also had trouble with the DC spike, so I used the SDRplay's options to get rid of it. I could've used HDSDR, but I may want to record this sometime and HDSDR doesn't apply its IQ compensation to recordings, so it's good to know how to do it in hardware.

This waterfall spans 24 hours, from November 21, 2016 at 9:17 PM to 9:17 PM the next day. Each vertical pixel represents 1 minute, +/- 1 or 2 seconds. Center frequency is 874.8 MHz. Waterfall bandwidth is 2 MHz with a signal bandwidth of about 1.25 MHz.

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