DIGTRX - Bad Block Report (BBR)
Here is some information DIGTRX users may find helpful when trying to correct bad blocks using "Bad Block Report".
Block zero must decode for MapMaker (MM) and Bad Block Report (BBR) to be available.
Now, with DIGTRX versions after 1.46, more than six blocks may be bad.
If a station copies a transmission with one or more bad blocks, he may request the corrected blocks only, be sent to correct his received file.
If this station did not have the Bad Block Report option turned on, he will still be able to make a Bad Block Report by clicking MMK and OK. This will store the received file in the Corrupt folder #1. Then by clicking BBR, the Bad Block Report will be created. Clicking Transmit will send the Bad Block Report to the original sending station.
Before the sending station can accept a Bad Block Report, the Bad Block Report option must be turned on. See Setup, Auto, open MapMaker/Bad Block Report. In order to decode the single block Bad Block Report, the RDFT 2.02A (or later) version decoder must be installed.
Once the original sending station has the Bad Block Report, he must answer YES to the question, "Do you want to codify a file with these blocks ?". When the WAV file is ready, he should click TRANSMIT.
Once the receiving station decodes the corrected blocks, the image is instantly repaired and displayed.
Example:
Art sends pic1.jpg to Bill.
Bill decodes pic1.jpg with two bad blocks.
Bill sends a Bad Block Report to Art.
Art encodes and sends the correction blocks to Bill.
Bill's pic1.jpg is fixed !
In addition, relay stations may assist in the replay of the Bad Block Report and correction blocks.
If more than one station requires correction, the sending station may accept a Bad Block Report from another station after the first is fixed.
A relay station may also receive a Bad Block Report and send the correction blocks. To do this, the relay station must have the file correct. He would then Replay (and recodify) the file before any other RDFT transmissions are received. Instead of replaying the full transmission, he must transmit about two seconds of the transmission then abort by clicking TRANSMIT a second time.
This sets up the relay station for accepting a Bad Block Report. After receiving the Bad Block Report, he is able to codify the correction blocks.
Example:
Art sends pic1.jpg.
Bill decodes pic1.jpg with two bad blocks.
I receive pic1.jpg without error.
I Replay (and recodify) this file before any other RDFT transmissions are received.
I transmit just two seconds of this file then abort.
Bill sends a Bad Block Report.
I receive the request for the correction blocks.
I encode and send the correction blocks to Bill.
Bill's pic1.jpg is fixed !
If you would like to e-mail me: djones@tima.com
Thank you for viewing my DIGTRX Bad Block Report web page. Enjoy your digital SSTV !
Dave Jones KB4YZ