# Change bitrate dynamically in tunnel.py **URL:** \ **Category:** GNU Radio\ **Created:** [January 9, 2012, 8:17am UTC](https://www.ruby-forum.com/t/change-bitrate-dynamically-in-tunnel-py/215576 "2012-01-09T08:17:44Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![dubstep](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/cdc98d/32.png) [@dubstep](https://www.ruby-forum.com/u/dubstep)\ **Post date:** [January 9, 2012, 8:17am UTC](https://www.ruby-forum.com/t/change-bitrate-dynamically-in-tunnel-py/215576/1 "2012-01-09T08:17:44Z")
Hi all, Now I use tunnel.py with USRP2. I set bitrate when I run tunnel.py. I cannot change the bitrate until I finish tunnel.py. But, I want to change bitrate dynamically when I am running tunnel.py. Does anyone know the ways to change bitrate dynamically? regards, kouta ---
**Author:** ![Kouta\_NISHIDA](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/858c86/32.png) [@Kouta\_NISHIDA](https://www.ruby-forum.com/u/Kouta_NISHIDA)\ **Post date:** [January 10, 2012, 1:38am UTC](https://www.ruby-forum.com/t/change-bitrate-dynamically-in-tunnel-py/215576/2 "2012-01-10T01:38:55Z")
On Mon, Jan 9, 2012 at 2:24 AM, Kouta NISHIDA \< [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)\> wrote: > regards, > kouta Hi Kouta, It’s not set up to work that way right now, but you should be able to hack it to do what you want. There are a couple of settings that affect the bitrate: the rate of the USRP and the number of samples per symbol (sps). In the current implementations of the PSK modulations, you can set a real number for the sps, so you should be able to change that to affect the bit rate. But remember, look for any place that is used since you’ll have to also reset the taps for the filters on both the RX and TX sides. You can also set the sample rate of the USRP as well to affect this. Let us know how you do with this. Tom ---
**Author:** ![Kouta\_NISHIDA](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/858c86/32.png) [@Kouta\_NISHIDA](https://www.ruby-forum.com/u/Kouta_NISHIDA)\ **Post date:** [January 10, 2012, 9:39am UTC](https://www.ruby-forum.com/t/change-bitrate-dynamically-in-tunnel-py/215576/3 "2012-01-10T09:39:00Z")
Tom R. wrote: > ``` > But, I want to change bitrate dynamically when I am running tunnel.py. > > ``` > > hack it to do what you want. > Let us know how you do with this. > > Tom Thank you for your advice. I will try setting the sample rate of the USRP to change bitrate dynamically. I found the parameter that Actual Bitrate with pick\_bitrate.py Is the sample rate of the USRP Actual Bitrate ? Would you tell me it if there are the file and parameter that I should pay attention to ? regards, kouta ---
**Author:** ![Kouta\_NISHIDA](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/858c86/32.png) [@Kouta\_NISHIDA](https://www.ruby-forum.com/u/Kouta_NISHIDA)\ **Post date:** [January 15, 2012, 6:49pm UTC](https://www.ruby-forum.com/t/change-bitrate-dynamically-in-tunnel-py/215576/4 "2012-01-15T18:49:33Z")
On Tue, Jan 10, 2012 at 3:37 AM, Kouta NISHIDA \< [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)\> wrote: > > > > dynamically. > > I found the parameter that Actual Bitrate with pick\_bitrate.py > Is the sample rate of the USRP Actual Bitrate ? > > Would you tell me it if there are the file and parameter that I should pay > attention to ? > > regards, > kouta Kouta, If you’re still using the pick\_bitrate.py file, it sounds like you are on an older release (pre 3.5). In that case, you might have more trouble changing the bitrate (at least arbitrarily). But if you are using that version, you use that script to set the interpolation or decimation rates of the USRP as well as the number of samples per symbol based on a desired rate. So using it, if you want to set a new bit rate, you will receive new values for both of these parameters. Tom