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The cost and viability of mobile CCTV

CCTV has undergone many changes in the past few years. With the improvements in compression technology and the wider availability of bandwidth, remote monitoring has become a viable reality at affordable rates.

In any deployed platform the tradeoff between cost, frame rate, bandwidth utilisation and image quality have been the key indicators to a viable solution. With fixed local bandwidth being effectively sold by the megabyte, this tradeoff still holds true and optimal compression still translates to the most cost effective solution – the less you use the lower the cost.

Once you move to mobile CCTV this becomes a critical success factor. Currently, bandwidth retails at around R2 per MB of data used. If you work on streaming video at 8 Kbps, you will use under 4 MB in an hour (or under R8 per hour at retail rates.) If you need 32 Kbps per second to transmit video you will use 16 MB per hour approx or around R32 per hour of your streaming video.

In addition, vehicles tend to move out of urban areas. If one looks at network availability, data is typically available in GPRS or possibly Edge once one moves out of the main urban areas. (3G is effectively restricted to major urban areas.)

In deploying a mobile CCTV platform one needs to take this into consideration and plan for a solution which can operate in a GPRS environment, as this is the most common bandwidth available. GPRS is an asymmetrical technology. What this means is that the downstream capacity is usually about four times greater than the upstream. One may ask so what?

SerVision bus project

Well, if you are reliant on GPRS and you install the mobile DVR in the vehicle and use GPRS you will only have access to upstream capacity of approximately 12 to 24 Kbps (or 1,5 to 3 KBps) to transmit video back to your control room or monitoring site.

The net result is that if you use a DVR that requires more than say 15-20 Kb of data per second to stream you will not receive video from a vehicle driving in a non 3G or edge area. The implication here is that your investment in live streaming is then only partially effective especially if you are involved in longer haul transport.

SerVision was recently deployed in a pilot government tender and was installed into five departmental vehicles. The units are able to stream 4 frames per second at 8 Kbps and thus meet the requirements to be able to deliver video over GPRS. Once in Edge or 3G the operators are able to stream at greater rates if required.

The ability to record at a good quality while still maintaining a live stream allows the operators to view live video from the vehicles via a Windows mobile cellphone or via the control room PC.

There is no doubt that mobile surveillance will continue to grow. With the complexities involved in ensuring that adequate compression is used, cellular modems are correctly installed for optimal network access and the variations encountered on optimising network access are dealt with, it is critical to do your homework and ensure that the device will meet and deal with all the issues discussed above.

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