Some sideband and carrier matters

Receiving data is best using only one of the sidebands of the AM signal. This can be done by using a narrow AM filter (normal is 6 to 9 kHz, use 3 to 4 kHz instead) and tuning to the carrier and one of the side bands. Alternatively you can use USB or LSB.

Receiving both sidebands can be a problem if propagation distorts both sidebands differently, which is often the case. Using only one sideband prevents this, giving a better reception.

Using a synchronised AM detector for digital signals most often isn’t an improvement, because both sidebands are used then too.

Synchronised AM can improve music quality though. With very deep QSB often the carrier dissapears partly or competely. This can cause distortion similar to receiving SSB on an AM receiver, which can be quite catastrophic for your music experience.

A synchronised AM detector introduces it’s own carrier, which always has the appropriate level, keeping it in sync with the original carrier, even if it dissapears for a short while, hence improving audio quality very much during those instances.

Next Slow Scan Radio is at August 1, 1830 UTC

Slow Scan Radio brings you several SSTV images and several minutes of data via short wave radio in AM. We are on 6070 kHz via Channel 292 each Wednesday, 1830 UTC, which is 2030 Central European Summertime.

Next show we will start with a digital overview of which SSTV modes and data types we will bring, so you will know those details beforehand in case you want to do those settings manually. We will transmit that list in MFSK64 and most probably also in PSK63R with 32 carriers.

Response to the first broadcast by the way was quite overwhelming. Everyone thanks for mailing your reports and comments on the show! It is very much appreciated!! (Mail Address you can find on the right side of this page, almost at the start of the page.)

Software and Apps to Decode the Images and Data in the show

Most recent software packages for SSTV on ham radio bands will work fine. I use both MMSSTV and QSSTV myself for the show (the first is a Windows program that does work fine under Wine on Debian systems.like Ubuntu, Mint et cetera. QSSTV is native for Linux and can be installed on many systems using package managers (for instance Synaptic) or using apt-get or similar when using a terminal window.

If you have Android than the app “Robot 36” is a good choice, on iOS you can use CQ SSTV.

The apps often even perform better, especially with QRM than the PC programms. I have no idea why.

If you can choose to use an audio cable, then do! You might however have fairly good result with a microphone for the receiver speaker. Please keep the distance between speaker and mic as short as possible, and also use the lowest audio level that will work. Too much audio causes “ghost” images (pictures that are vageu and have double edges), because of reflections of the audio in the room where you are.

Data

For the data I use Fldigi. Other choices will also work in most cases. Some modes might not be in other programs or might be exclusive for Fldigi. The same as with SSTV goes for data concerning using an audio cable. But the faster mode’s might only work using such a cable.

There also is an Android version of Fldigi, which has a somewhat limited operation, this app is called AndFlmsg.

Software:

MMSSTV:

http://hamsoft.ca/pages/mmsstv.php

Fldigi for PC:

http://www.w1hkj.com/

Android version:

http://www.w1hkj.com/vk2eta

 

Slow Scan Radio start 25 juli

Next Wednesday a new weekly radio show, Slow Scan Radio will start at 6070 kHz (49 meter band), containing lot’s of SSTV images and digital data. The show will start with spoken news on ham radio related topics in English. Most probably the show will start at 2030 CET Summertime (1830 UTC).

More details will follow soon


A.s. woensdag start een nieuw wekelijks radioprogramma Slow Scan Radio (in het Engels) met veel SSTV en digitale data, maar ook met amateurnieuws op 6070 kHz. Begintijdstip van de uitzending is waarschijnlijk 2030 uur CET (1830 UTC).

Meer informatie volgt