# Testing FLEX modems with gnuradio **URL:** \ **Category:** GNU Radio\ **Created:** [February 14, 2014, 12:32am UTC](https://www.ruby-forum.com/t/testing-flex-modems-with-gnuradio/239146 "2014-02-14T00:32:36Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Detlef\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/58f4c7/32.png) [@Detlef\_R](https://www.ruby-forum.com/u/Detlef_R)\ **Post date:** [February 14, 2014, 12:32am UTC](https://www.ruby-forum.com/t/testing-flex-modems-with-gnuradio/239146/1 "2014-02-14T00:32:36Z")
I am new to gnuradio and have spent the last few days reading every tutorial I can find. I have set up both 3.7.1 and 3.6.5 in separate test environments in 2 VMs. I am using a BladeRF SDR with dual 900MHz antenna. I’ve been asked to test 2 devices which will controlled remotely over the FLEX paging network. I can see some blocks have been built into gnuradio-companion, FLEX Deinterleave and FLEX Synchronizer. I also found some samples here [GitHub - argilo/sdr-examples: A collection of GNU Radio flow graphs](https://github.com/argilo/sdr-examples) but I think these were built for a different version of gnuradio possibly. When I run the python script pager\_rx.py or pager\_rx\_929.py it pops up with a nice waterfall display and I even get some text decoded signals in the terminal window, but within a few seconds the display goes gray and I cannot change any of the sliders and must force quit to get out. I loaded the multi\_tx.grc in gnuradio-companion just to get an idea of how to build a flow chart for FLEX, but I get some errors about missing blocks. Loading: “/home/test/sandbox/gnuradio-builds/sdr-examples/multi\_tx.grc” > > > Error: Block key “iqbalance\_fix\_cc” not found in Platform - grc(GNU > > > Radio Companion) > > > Error: Connection between blocks\_add\_xx\_0(0) and iqbalance\_fix\_cc\_0(0) > > > could not be made. > > > sink block id “iqbalance\_fix\_cc\_0” not in block ids > > > Error: Connection between iqbalance\_fix\_cc\_0(0) and > > > blocks\_add\_const\_vxx\_1(0) could not be made. > > > source block id “iqbalance\_fix\_cc\_0” not in block ids > > > Done If I’m going to build my own flowcharts, I’ll need to know what the blocks in the existing flows are doing, but I haven’t seen any good resources for that. If I can get some of the existing scripts to run properly that might help as well. Any suggestions on that? Here is the output when I run the pager\_rx.py gr-osmosdr v0.1.0-66-g154c4ddd (0.1.1git) gnuradio 3.7.1 built-in source types: file fcd rtl\_tcp bladerf rfspace [bladeRF source] Using nuand LLC bladeRF #0 SN 909d…c10c FW v1.6.1 FPGA v0.0.2 According to the readme this script is meant to be used with an RTL-SDR rather than my BladeRF but it seems to detect the blade and I don’t see any hardware specific modules being imported. Am I missing something? ---
**Author:** ![Al\_Smith](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/858c86/32.png) [@Al\_Smith](https://www.ruby-forum.com/u/Al_Smith)\ **Post date:** [February 14, 2014, 12:40am UTC](https://www.ruby-forum.com/t/testing-flex-modems-with-gnuradio/239146/2 "2014-02-14T00:40:15Z")
Clayton’s sdr-examples are for GnuRadio 3.7.1. Your issue is that you haven’t built gr-iqbal. It’s not really needed, so you can just delete that block in the graphs. Ron ---
**Author:** ![Al\_Smith](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/858c86/32.png) [@Al\_Smith](https://www.ruby-forum.com/u/Al_Smith)\ **Post date:** [February 14, 2014, 4:59am UTC](https://www.ruby-forum.com/t/testing-flex-modems-with-gnuradio/239146/3 "2014-02-14T04:59:22Z")
I’ve tried pager\_rx.py on bladeRF, and it works fine here (GnuRadio 3.7.2.1 and Ubuntu 13.04). Tons of traffic on channel 25 here in Silicon Valley. I’ve made some changes to the code to work better with bladeRF (mostly with the gain setting). [http://www.w6rz.net/pager\_rx.py](http://www.w6rz.net/pager_rx.py) When a flow grays out and you have to force a quit, it usually means you don’t have enough CPU cycles. However, at 1.2 Msps, pager\_rx.py isn’t really taking much CPU. Perhaps it’s your VM? Ron