Cowan A3 and DVB-T tuner: Some tests (kinda long and photo-heavy)

Hitman Actual

This post should be of interest to all you Cowan A3 owners out there. Last week I picked up the optional DVB-T tuner in Pixmania, and proceeded to run a few tests to see if it would work in the Irish DTT regions.To those who don't know, there is currently a trial being run in Dublin and Louth, and while many of the channels are encrypted, it is possible to pick up the four terrestrial channels, as well as about ten radio stations, in digital broadcast form. For more on this, there are a couple of excellent stickies over on the Terrestrial forum.


So the Cowan tuner: It's designed to pick up 1-SEG (Japan), DMB-T (China), and DVB-T signals; for Europe, DVB-T is the accepted standard. For any tech-heads, here's the spec, and a picture of the tuner:






Here's what it looks like connected to the A3:





First test: Blanchardstown
Some background first. I'm currently able to receive the Irish DVB broadcast in the Blanchardstown area using a basic Hauppauge HVR1100 Digital/Analog tuner card and a bog-standard €15 indoor antenna from Maplins. The transmitter for the Dublin area is situated in Three Rock (Dublin Mountains), although it's relatively low-power at only 25kW ERP. But even with this low(ish) power transmission and cheapo equipment, I can receive the digital broadcast perfectly.


So my first test was obviously to see if I could receive the same signal using the Cowon. Doing a channel scan using both the Cowan-specific “Ireland Region” and “UHF8 Mhz”, I was able to pick up some of the encrypted channels, as shown below, but none of the four terrestial channels. But on a better point I could occasionally listen to one of the radio stations (Phantom FM, thankfully!), although these were being listed on the player using transmission-specific codes (2830, which I think is the Service ID number transmitted in the DVB packet for Phantom). So at least I had some confidence that the tuner was functional, and compatible with Irish DTT broadcasts.





Second test: Sandyford
To do a better test of the Three Rock mast, I headed to Sandyford which is within 2km of the transmitter. Unfortunately, still no great success: I was able to pick up more signals but I couldn't view any of them properly. Also, they were displayed in Service ID form, and I was picking up 2901 to 2906; 3901 to 3906; 4901 and 4902. Incidentally, 4901 was interesting as the player returned an error message complaining about not having the right H.264 CODEC for the signal, which makes me think this was the special MPEG4 test signal.


Third test: Clermont Carn
Clermont Carn is the transmitter near the NI border in Louth, and is much more powerful than the Three Rock mast, at 300kW ERP. So I was much more optimistic that I could get a signal from this mast. I just did one test, about 15km from the mast on the Castleblaney road, and finally saw some success. This time, the channel scan returned a mix of Service ID and proper channel names (see picture below), and I was able to view the four terrestrial channels on the service ID's 1901 (RTE1), 1902 (NET2), 1903 (TV3), 1904 (TG4).



However, the reception wasn't perfect. Sometimes the sound wouldn't play, and other times the playback would slow-down to about 1FPS. But when it was stable... Wow! The reception and sound were awesome, absolutely crystal clear. Below are a couple of screenshots I took, and the playback was as clear as shown in the shots.


Screenshot 1:



Screenshot 2:



So my conclusions so far are that the tuner won't currently work with the lower-power Three Rock mast, so it's a waste of time for Dublin A3 owners. But it may be worthwhile trying it out nearer to the Clermont Mast to see if operation improves, as in fairness I was about 15km away from the mast and only did some limited testing.

I'll also probably take the tuner apart soon anyway to spec it out and see if any mods can be done to improve it.

maxg

There is no problem with the power of the 3rock transmitter. There is a problem with the offset used for the frequency carrying the irish channels.
If there is a manual scan option try 737833 for the frequency.

watty

However Europe is migrating to MPEG4 for standard DTT to save 50% space.

The current transmission in Ireland is just a trial and they have commited to MPEG4. DVB-h tests are ongoing too.

So the TV part of this could be fairly obsolete soon. Also there is a risk that Ireland will use a viewing card tied to payment of TV licence.


DO NOT buy anything for Irish DTT till at least the Autumn. Even then the spec is likely MPEG2/MPEG4 (even for SD, not just HD) and MHEG5 for interactive/Guide.

Hitman Actual

maxg wrote: »

There is no problem with the power of the 3rock transmitter. There is a problem with the offset used for the frequency carrying the irish channels.
If there is a manual scan option try 737833 for the frequency.

Okay; I assumed that when I could view signals from Clermont Carn, and not Three Rock, transmitted power was an issue.

Unfortunately, you can't do a manual select for an exact frequency. The options are "Ireland Region", "UHF 8MHz", "UHF 7MHz", "UHF 6MHz", and only the first two of those return any channels during a scan anyway.

Can you tell me the frequencies used by Clermont Carn for the four terrestrial channels?

Hitman Actual

watty wrote: »

However Europe is migrating to MPEG4 for standard DTT to save 50% space.

The current transmission in Ireland is just a trial and they have commited to MPEG4. DVB-h tests are ongoing too.

So the TV part of this could be fairly obsolete soon. Also there is a risk that Ireland will use a viewing card tied to payment of TV licence.


DO NOT buy anything for Irish DTT till at least the Autumn. Even then the spec is likely MPEG2/MPEG4 (even for SD, not just HD) and MHEG5 for interactive/Guide.

Technically, the player supports MPEG4, but the early firmware versions are buggy. But, yes, the tuner seems to only be MPEG2-compliant.

watty wrote: »

Also there is a risk that Ireland will use a viewing card tied to payment of TV licence.

This seems a bit draconian. Competition laws?

DVB-H sounds interesting, what stage is that at now?

zilog_jones

Surely it's the player that does the video decoding, and the tuner add-on is just a tuner, i.e. later firmware may be able to receive MPEG4 DVB-T? Then again this is Cowon we're talking about I have an i7 - the sound quality is excellent, but there's sooo many things they could do with fixing firmware-wise...

Kinda weird that it does 1-SEG but not DVB-H (our equivalent), which should be much more suited to portable devices like this. Are they still doing DVB-H trials in Dublin?

maxg

lenny_leonard wrote: »

Okay; I assumed that when I could view signals from Clermont Carn, and not Three Rock, transmitted power was an issue.

Unfortunately, you can't do a manual select for an exact frequency. The options are "Ireland Region", "UHF 8MHz", "UHF 7MHz", "UHF 6MHz", and only the first two of those return any channels during a scan anyway.

Can you tell me the frequencies used by Clermont Carn for the four terrestrial channels?

The frequency for the irish channels via Clermont is 730000.
The software at your device is searching at 738000 for 3rock but the real frequency is 737833. That offset was introduced to keep distance to the next analogue channel.
Try UK region as scan option. If that is not working its maybe possible to patch the frequency list for the scan.

Hitman Actual

zilog_jones wrote: »

Surely it's the player that does the video decoding, and the tuner add-on is just a tuner, i.e. later firmware may be able to receive MPEG4 DVB-T? Then again this is Cowon we're talking about I have an i7 - the sound quality is excellent, but there's sooo many things they could do with fixing firmware-wise...

From what I understand of the technology, the tuner just demodulates the received RF and converts it to an MPEG2 transport stream, sending it to the player on the USB port. The player does the rest. If that's correct, then for MPEG4 you'd need a dedicated tuner, but if the player can already (almost!) support MPEG4/H.264, then I don't see why it shouldn't be possible to handle MPEG4 broadcasts. It's hard to say without knowing the player architecture, though.

zilog_jones wrote: »

Kinda weird that it does 1-SEG but not DVB-H (our equivalent), which should be much more suited to portable devices like this. Are they still doing DVB-H trials in Dublin?

I'd guess that DVB-T is much more established than DVB-H at the moment, so they went with the safer option.

Hitman Actual

maxg wrote: »

The frequency for the irish channels via Clermont is 730000.
The software at your device is searching at 738000 for 3rock but the real frequency is 737833. That offset was introduced to keep distance to the next analogue channel.
Try UK region as scan option. If that is not working its maybe possible to patch the frequency list for the scan.

I've tried a few different regions (UK included), but I can't pick up the four main channels. What you're saying makes sense though. I think I've seen every channel listed on the 730/770/794MHz frequencies at some stage, but none at the 737.833MHz frequency. So hopefully a firmware update should fix this, but if it's a tuner limitation, then I'm screwed.

maxg

Is the latest firmware update installed.
If yes check if you can find the frequency list for the scan in the system folder.

Hitman Actual

Thanks for the tip, maxg; that worked! There's a simple text file that you just need to edit: I just added in the 737833 frequency and I can pick up the relevant channels now.

I also just did a 'commuter train test' which is fairly central to what Mobile TV is all about. I checked the reception of the Irish channels from Coolmine station to Connolly, and results were mixed. Before Drumcondra, reception is patchy at best- okay in flat, open sections but poor in sections where the track is lined by trees or otherwise obscured. From Drumcondra to Connolly (where the track is raised to roof-level of the surrounding houses), it worked really well, with the reception practically flawless, except when passing Croke Park (which is understandable).