BATC DTX1 Questions and Answers

[G8GKQ]

Please post your BATC DTX1 Questions and Answers here for the benefit of other members.

[M0ATV]

Besides the suggestion for using a temp inline duplexer/triplexer to aid with filtering of output prior to input to final amp, what other methods are easiest for filtering output.

[G8XZD-TV]

Compared to the SR systems "Hamset" boards - is this a step forward - or essentially the same technology presented in a different way?
(and less hassle to get hold of in the UK)

[g4wvu]

Might be able to answer a few Qs. Been playing around with a pre-production (Beta FW) DTX1 for some months.
Essentially does the same job as an SR systems DVB-S unit (MPEG encoder is a Fujitsu LSI chipset , onboard 140-2150 mhz synthesizer & QPSK modulator, Xilinx FPGA doing the framing & coding etc.) However its all on one board having been designed for DVB-T commercial distribution use originally (Hotels, corporate etc.) It has a header for external MPEG 2( or possibly MPEG4 soon) encoders, so is expandable to multi TS. Inputs are all on the rear & no multiway ribbon cables or connectors to displays or controllers are required. The only connections required are 6 wires for 5 switches (5+ 1 common) to directly control all parameters - shown on a two row display on the board edge.

I have one here (cased version) & its perfomance is as good or better than the SR unit I also have in most areas. Max RF output level is around -5dBm (as opposed to +4) ....only possible minus, but the level range is much wider (100 steps at ~0.5dB as opposed to only 15 rather coarse on my SR). Close in spectral purity is better (I think sharper (Bessel) filters on the I Q signals) by about 10dB generally. Generally a good piece of kit for generating DVB-S at a very reasonable price(via BATC - board version). Unit additionally has 3 memories which are usefull

[g8gtz]

A question has been asked by Mans 9H1GB on email and answered as follows -posted FYI:

Question:
Apart from the assembled board, does it come with the 5 switches for up,down, left, right, OK buttons and the RS232 cable.

Answer:
The bare PCB system at £399 only has the display and not the switches nor the RS232 cable – the wiring for the keys is in the user guide at http://www.dtx1.info/

The system with case parts (out of stock until next week) comes complete with case and front panel with switches.

[peterschrader2]

Has anybody tried to set the symbol rate to 4.268 MSym/s, out local ATV repeater requires this symbol rate. I've got the DTX going across the room at 4.2M to a SelectTV STB no problems.

Or ca the Sym rate be set to a custom figure using the RS232 interface?

[2E0DTX]

Hi Peter

Symbol rate can be set in 100kHz steps presently. Do you need more accurate than that?

Please drop an email to support@dtx1.info and we can discuss offline.

Thanks

Laurence M6TTX

[g4wvu]

4.268 MSym/s .......interesting / strange SR for a repeater input ?

[vk4xrl-DATV]

4.268 MSym/s .......interesting / strange SR for a repeater input ?
Why so its a valid SR input?

[g4wvu]

4.268 MSym/s .......interesting / strange SR for a repeater input ?
Why so its a valid SR input?

Just seems an odd number - i.e. why not round up or down to the nearest hundred e.g 4.2MS or 4.3MS (or even just 4MS/s ) etc.
The extra 68KS or 32 less, wouldn't make any practical difference to the effective video quality for DATV purposes. Many coders / modulators will only cater for a fixed spread of rates, often at multiples with 0s e.g. 2000, 3000, 4000 etc.

http://www.spectra-bv.nl/dvb_modulator_lband.html . DTX1 also is adjustable to the nearest 100KS/s (at the moment - I hasten to add - sounds from one of the replies like a FW edit. might be in the pipeline!)