Pira.cz Technical Forum

FM Analysis => PIRA75 FM Analyzer => Topic started by: jadertecnico on June 30, 2012, 02:51:49 pm

Title: Pira 75 in distorted audio output
Post by: jadertecnico on June 30, 2012, 02:51:49 pm

After I updated my pira75 of 1.3b to 1.3a on the audio output was distorted! how to solve? or I have to revert the firmware.

Title: Re: Pira 75 in distorted audio output
Post by: Jan on June 30, 2012, 07:30:09 pm

Try the latest firmware 1.3c rev. 2.
Set the volume to 0 dB in menu and limit the volume by the potentiometer.

Title: Re: Pira 75 in distorted audio output
Post by: jadertecnico on July 01, 2012, 09:33:50 pm

did not change anything! remains fuzzy and when he served in the volume nothing happens!

Title: Re: Pira 75 in distorted audio output
Post by: Jan on July 02, 2012, 08:25:26 am

It has probably nothing to do with the firmware. As entire demodulation process is DSP based, it works the same way on all devices. Does the distortion occur on one station or all stations? What's the 2nd IF value and typical deviation MAX value? Do you use headphones, audio amplifier, soundcard? Do the other devices sound ok? Some more information, connection photos, reports or pictures from the software would be very appreciated if showing any non-standard behavior. Problem of this kind hasn't been reported yet. If you wish you may send the unit to our servicing address so I'll look at it.

Title: Re: Pira 75 in distorted audio output
Post by: Jader on July 02, 2012, 02:53:09 pm

Jan expensive, 2 IFs is in 325khz, use a sample to an RTA AUDIO. I still believe is the firmware for co happened when replacing 1.3a to 1.3c. VOLUME not the function operates. tripont only. how to revert the firmware? if so please pass me the 1.3a.

Title: Re: Pira 75 in distorted audio output
Post by: Jan on July 02, 2012, 03:20:49 pm

I don't think the firmware downgrade will solve the real cause but I'm providing it of course.
Download here: http://pira.cz/fm_broadcast_analyzer/fwup-p75-13a.zip (http://pira.cz/fm_broadcast_analyzer/fwup-p75-13a.zip)
Looking for the result  ???

Title: Re: Pira 75 in distorted audio output
Post by: Jan on July 02, 2012, 05:26:35 pm

The solution is finally known. After installing firmware 1.3a tune to 89.2 MHz, make sure Measuring is enabled, then select Save settings. Then update to version 1.3c.
There are more methods how to solve it but this is fastest. The reason is in different memory assignment between versions 1.3a and 1.3b due to memory usage optimization.
It will be fixed in the next version so that user can migrate between versions without need to read the migration notes.  ;)

Title: Re: Pira 75 in distorted audio output
Post by: Jader on July 02, 2012, 07:02:46 pm

was perfect! thank Jan.