Class 345 OPO CCTV System

[RF Repeater]

I hear that the Class 345 OPO CCTV System uses leaky feeder under the platform edge lip to transmit the signals tio the trains, like on the Jubilee Line.
But looking at photos I can't see the antennas under the drivers cab like they are on the Jubilee Line stock.
Does anyone know more about these antennas, where they are positioned and who makes them for Bombardier?

 

[Watto1990]

The Leaky Feeder Receivers on a Class 345 are located on the bogies at the No. 2 end of the MS1 and MS2 vehicles (the bogies closest to the centre of the train on the third and fifth vehicles on a 7 car unit or on the third and seventh vehicles on a full 9 car unit).

 

[RF Repeater]

Hi Watto - thanks for that info!
That's interesting then, because on the Jubilee et al trains the antennas are under each cab, with the rear ones always active. This means that the OPO picture is not displayed in the cab until the train is fully in the platform. When the train leaves, the rear antennas operate the length of the platform, so the driver always has a view of the platform until the train has left the station.

So on Crossrail, with the antennas pretty much in the centre of the train, and if the leaky feeder runs just the length of the platform like the Jubilee et al, the driver will only see half of the platform as he leaves the station, meaning that if someone fell under the last half of his train, he couldn't spot it and slam on the brakes.
That is, unless, the leaky feeder extends from the platform and down the track for half the platform length?
Any thoughts?

 

[Domh245]

If the monitors behave in the same way as other mainline stock, they'll turn off at about 3mph anyway so the fact that the feed stops halfway down the platform shouldn't matter by then.

 

[RF Repeater]

Ah, that's also interesting. The LU stock doesn't do that, it stays on until they have left the station and then when there is no RF (thus video) signal received, the screen goes blank, so they are not dependant on speed, but limitation of the length of the leaky feeder.
Does anyone know if Bombardier make the train borne antennas? At around 60MHz reception it would be an interesting design!

 

[507 001]

Cross rail has platform doors throughout the core doesn’t it? No chance of anybody falling under the train there!

 

[RF Repeater]

Cross rail has platform doors throughout the core doesn’t it? No chance of anybody falling under the train there!

Ah, only at the 8 new underground stations. According to Crossrail puff, that’s roughly 4km of platform edge screens in total!

 

[RF Repeater]

Thinking more about the antenna situation on the Class 345s, why would there be two antennas in the middle of each side of the train? Why not just one each side? It makes sense to have two on each side of eg Jubilee, as they are under the cab ensuring the whole length of the platform can be seen by the driver. But if Class 345 only sees just under half the platform anyway, why not just have the one antenna?

 

[Domh245]

I would guess redundancy. If you've only got 1 per side and it fails for whatever reason then you'll have to take the train out of service

 

[rebmcr]

Thinking more about the antenna situation on the Class 345s, why would there be two antennas in the middle of each side of the train? Why not just one each side? It makes sense to have two on each side of eg Jubilee, as they are under the cab ensuring the whole length of the platform can be seen by the driver. But if Class 345 only sees just under half the platform anyway, why not just have the one antenna?

345s (like most modern EMUs) are formed of two semi-independent half-sets.

 

[RF Repeater]

345s (like most modern EMUs) are formed of two semi-independent half-sets.

Ahah, that would explain it. So the antennas are at the back of the train, albeit the back of the semi-independant half-set. That allows the OPO system to be completely independant per EMU half-set, with the downside that only the last half of the platform is seen by the driver as he leaves the "overground" station. I say overground, because the driver does not need to see the "underground" platform, beacuse once they have closed the doors, the platform edge screens shut, and the platform is safe.

 

[RF Repeater]

Now my next puzzle on this obscure yet fascinating transmission system, is about how the platform images are displayed on the Class 345 in-cab OPO CCTV monitors, as per the photo enclosed.
On this particular platform, there are 4 cameras "cropped and spliced" together.
As you can see they are displayed on the LCD in a 16/9 format (ie black bands at the top and at the bottom of a 4/3 LCD screen). Also known as "letterbox" format.
This implies that the platform cameras are 16/9, which strikes me as a bit odd, almost an overkill as they are cropping out such a small image.
Does anyone know more about the platform side of this video processing system?

 

[Fincra5]

Now my next puzzle on this obscure yet fascinating transmission system, is about how the platform images are displayed on the Class 345 in-cab OPO CCTV monitors, as per the photo enclosed.
On this particular platform, there are 4 cameras "cropped and spliced" together.
As you can see they are displayed on the LCD in a 16/9 format (ie black bands at the top and at the bottom of a 4/3 LCD screen). Also known as "letterbox" format.
This implies that the platform cameras are 16/9, which strikes me as a bit odd, almost an overkill as they are cropping out such a small image.
Does anyone know more about the platform side of this video processing system?

Really thats how you need them. What you need to see on DOO is the full side of your train and part of the platform, so ensure the doors are clear. No need to see the very far side of the platform.

 

[rebmcr]

Now my next puzzle on this obscure yet fascinating transmission system, is about how the platform images are displayed on the Class 345 in-cab OPO CCTV monitors, as per the photo enclosed.
On this particular platform, there are 4 cameras "cropped and spliced" together.
As you can see they are displayed on the LCD in a 16/9 format (ie black bands at the top and at the bottom of a 4/3 LCD screen). Also known as "letterbox" format.
This implies that the platform cameras are 16/9, which strikes me as a bit odd, almost an overkill as they are cropping out such a small image.
Does anyone know more about the platform side of this video processing system?

That's not 16:9, it's just the result of putting those four vertical panels alongside each other.

 

[RF Repeater]

As a special treat after InfraRail, I waited for a Class345 from Stratford to Liverpool St.
Photos show the OPO antennas exactly where "Watto" told me (thanks Watto!) - see photos.
I was shown around the cab by a nice driver who said that the OPO wasn't yet working at Liverpool St, so I couldn't see it on the screen!
An installer at Stratford who happened to be at the station told me the cameras are in fact 4/3, and they go into a digital processor which puts the 4 vertical panels alongside each other, so that ties in with "rebmcr", thanks!
All I'm curious now is to whether Bombardier made the antennas or not - any takers?