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Digithin help

Posted: Thu May 28, 2015 1:53 pm
by g8vpg
I've completed my Digithin today, but it is not producing a modulated output. I'm using a Rpi model B with camera and I know that this works OK in Ugly mode. The LED on the Digithin board is flashing. Using a 'scope, I am getting a similar waveform on pins 7 & 9 of the U2790B, which turns on and off as I enable the IQ output from the Rpi. I have noticed that the 5V output from the Rpi is running at 4.8V by itself, 4.7V with the Digithin plugged in. The onboard regulator is OK at 3.3V.
For the LO, I have been using my RF Explorer signal generator at 146.5MHz. I built the Digithin using the recommended values for VHF operation. I have used the -10dbm output from the sig gen, and used 3-9db extra attenuation. I am monitoring the output of the Digthin using the RF Explorer spectrum analyser and I am getting a carrier at about -27dbm, with LO at about -20dbm. Any suggestions would be gratefully received!
73 Shaun G8VPG.

Re: Digithin help

Posted: Fri May 29, 2015 6:08 am
by g8gtz
Hi Shaun,

This thread should be retitled "The joys of beta testing"!

Not sure if that is a hardware fault but probably because you are not running the correct version of RpiDATV code - you no longer use the UglyDATV code. In fact if you have a B model and it is not crashing you are not running the correct version - see below :-)

The latest versions are here ... 7kGOa?dl=0 and to be on the safe side I would build a new image using the .img in the sd card images folder.

In the RPI test software folder is a pdf with Brian's instructions.

Download and build the image and then copy the files in the test folder on dropbox - except the pdf - in to the RpiDATV folder using FTP, type "sudo su" and then chmod 775 *

I did not but if you decide to run the test software you will need to re-name RpiDATV-EWJ to RpiDATV and remove the -EWJ off the end of the TS file name.

If you are using a model B, before you run anything you must rename to another name (anything) - this is because this file contains the mapping of the GPIO port for the hardware switches which Evariste has implemented. However he has used pins which on the B are already used and if you don't rename this it will crash.

Once you have done that simply cd in to the RpiDATV directory type ./ and it should run....

You may need to set the video PID to 256 and audio to to 257 and when there is no external USB audio device it sends a series of test tones.

Evariste is working on the non development version of the code and it should be released shortly and will include control of the si570 oscillator module which I now have running using Brian's separate code.

Once running you should always get approximately 0 dBm out and an LO of -21 dBm at 146.5 seems optimum. It needs at least -25 dBm LO or it “crashes” (a bit of cliff effect if you go below that ) and above -10 dBm the MER degrades significantly. LO level between these limits has no real effect on output level.

Happy to talk you through this on Skype over the weekend.



Re: Digithin help

Posted: Fri May 29, 2015 8:06 am
by g8vpg
Thanks Noel,
That has restored my faith! I am running the old software, so will get some new SD cards and follow your instructions.
73 Shaun.

Re: Digithin help

Posted: Sat Jun 06, 2015 11:21 am
by g8vpg
My 8GB SD cards have now arrived. I downloaded (2 months old from Dropbox), unzipped it and created a new image using win32diskimager. However, when I insert it into the RPi, it does not appear to boot from it. Only the red pwr lamp lights on the Rpi board. It does not connect to the router via the Ethernet cable. I assume that to rename, I have to connect to it using something like Filezilla? Any suggestions would be most welcome!
73 Shaun.

Re: Digithin help

Posted: Sun Jun 07, 2015 9:05 am
by g8vpg
OK, I have now rewritten the img file on the SD card and the Rpi boots up OK. However, it seems to be crashing and it refuses to connect when I try from Filezilla. I cannot see the file Rpibuttons on Windows Explorer, so how do I rename it to stop it from crashing? I'm afraid Linux is a completely foreign language to me!
I've had a look at the Rpi output via an HDMI connection, and it gets as far as the login prompt and then goes into an endless loop.
73 Shaun.

Re: Digithin help

Posted: Sun Jun 07, 2015 2:33 pm
by G4EWJ
It seems like an SD card / image problem if it won't boot properly. I'm only a Linux beginner myself, but if you're available to Skype, we can pool our resources.