Daily Archives: 13th October 2016

Hakology – Retropie HDMI audio fix

No audio over HDMI on retropie? No problem, here’s your solution i’ve seen a few fixes on the web lots varied some were overly complicated so I decided to write up a really simple fix. Tested and working on the RPi3MB.

Boot retropie
Go to the retro pie menu
Go to the audio menu and press ‘A’
Ensure HDMI is selected, also check the mixer volume is at 100%
Save settings and return to the retropie menu
Quit emulation station
Run …
sudo nano /boot/config.txt

uncomment the following …
#hdmi_drive=2
so it looks like this …
hdmi_drive=2

also uncomment …
#hdmi_force_hotplug=1
so it looks like this …
hdmi_force_hotplug=1

Press ctrl+x to save the file.
now run …
amixer cset numid=3 2
and ..
sudo reboot

Hopefully you should now have audio over HDMI

Hakology Day 11 : Blog Entry

[1712]
Just doing some RL stuff will be on this evening. SD card for RPi3 has arrived and whiteboard pens. Multimon-ng running on linux logging data. πŸ™‚
[/1712]

[1904]
Munching food just about to get down to business.
[/1904]

[1909]
TODO:
-SDR# notes / audio / video
-POCSAG in PDW
-FLEX in multimon-ng
-Test RPi3 (with retropie of course)
-Check corsair ticket.
-VBLOG
-Audio working on RPi3 HDMI
[/1909]

[1920]
Whoot! looks like corsair have updated the ticket. Awaiting RMA confirmation swapping this brown mx for a new spangly red mx keyboard hopefully. That would be most awesome.
[/1920]

[2014]
Distracted by the internet again! … also reluctant to stop logging POCSAG messages … but I need the dongle.
[/2014]

[2102]
Rendering vblog
[/2102]

[2116]
Looking at demodulating FLEX using multimon-ng but IDK if I have the latest version compiled. Time for some updates.
[/2116]

[2124]
RPi3B vs RPiB there is no comparison, first impressions very impressed!
[/2124]

[2148]
RPi3 still updating & uploading vblog.
[/2148]

[2206]

[/2206]

[2224]
Rebuilt and installed latest version of multimon-ng. Now have FLEX messages demodulating whoot!
[/2224]

[2325]
Audio working on RPi3 Whoot!!! πŸ˜€
[/2325]

[0034]
Ready to record SDR# tutorial tomorrow.
On mumble with luc, hexon and gir.
Signing off for today, its been fun. πŸ™‚
[/0035]

[0147]
Worth an update thank you gir for offering to send a RPi zero for hakology to have a play with … can’t wait πŸ˜€
[/0147]

[0234]
Thanks hexon been after this link for a long time … http://playdosgamesonline.com
Ran by the creator of textfiles.com
[/0234]

Hakology – Introduction to SDR

What is SDR?

S.D.R. stands for Software Defined Radio.

SDR is a combination of hardware and software used to scan/monitor/demodulate/transmit electromagnetic radio signals.

Signals?

Signals can be used to transmit voice or data.
The most common methods of transmission are FM and AM.

FM = Frequency modulation

AM = Amplitude modulation

FM, modulates the frequency of the carrier wave to transmit a signal.
AM, modulates the amplitude of the carrier wave to transmit a signal.

Both can be used to transmit analogue or digital data.

SDR setup?

You will need …
PC / laptop – Laptop preferably for portability, currently running on an i5 2.4ghz 8gb ram pretty smoothly, I did try this on an older atom processor on linux using gqrx but latency was an issue.

SDR dongleΒ  – RTL2832U – If you want to follow along with the next few videos grab an RTL dongle you can always decided if you like the hobby enough to invest in more expensive equipment at a later date.

Antenna – You can use the one provided but its not recommended for the next few videos ill be using a cheap airband antenna I bought from ebay.

Realtek DVB-T+DAB+FM Dongle

RTL2832U – Notes: The dongle was never intended to be used for SDR but two researchers discovered the chip used was able to cover a wide range of frequencies (24 mhz – 1766 mhz) and decided to rewrite the drivers. (Antii Palosaari and Eric Fry of Osmocom) Since then the dongle has proved hugely successful with amateur radio enthusiasts.

So what can you do with SDR?

Voice, ADSB, ACARS, digital voice, AIS, POCSAG, FLEX, consumer devices, weather ballon data, HAM internet, DVB-T, GSM, GPS, spectrum analysis, weather satellites, ISS, radio astronomy, meteor scatter, FM/AM radio, RDS, DAB, RNG … probably much more!

Over the last few years lots of researchers and developers have started producing applications and code for the RTLSDR and hopefully many more projects to come as the community grows.

Keep tuned for more SDR fun stuff!

If you get bored in the meantime try googling some of the stuff I’ve listed above and start your own research / project / experiment / learning / hack / etc.

Useful links:
https://en.wikipedia.org/wiki/Radio
https://en.wikipedia.org/wiki/AM_broadcasting
https://en.wikipedia.org/wiki/FM_broadcasting
https://en.wikipedia.org/wiki/Software-defined_radio
http://www.sigidwiki.com/wiki/Signal_Identification_Guide