Squiffy

> Maplin Stock Code N80GC Ah, well that shows it as 50FPS per channel, which is more than necessary. Given that you don't actually need all of the features it provides, I would say it's a lot of money to pay for something that will probably disappoint you regarding the recording video resolution. Rather than wading through lots of manuals trying to find specs for DVRs, it would be great to see a table of recent and new models to make it easy to locate models which provide D1 resolution for example.

I can't see that model listed on the Maplin site, I assumed they'd phased out the Safe-Core models and only stocked Swann these days. Having said that it's probably all the same stuff anyway, just rebadged. I would think it's 12.5 FPS per channel at 720x288.

It simply provides an additional output to use as you wish. Video cable usually uses 75 ohm cable (and output stages), so it's important to retain the same impedance. Therefore it's not a good idea to simply have a "Y" connector on the output to feed into another device because if they're both 75 ohm impedance, the load will be 37.5 ohms. A loop through option makes it easier to couple the video signal to additional devices, if needed.

Which model? DVR-400M?

The recording FPS per channel often seems to be the hardest specification to pin down when reading manuals and feature lists, followed by the maximum recording resolution per channel. In one manual I read recently it gives two different maximum resolutions (one at the front of manual, the other at the back...). D1 resolution is necessary for good quality recording, while 25FPS per channel as an option is preferable (to me), I'd settle for half that for home CCTV use. I assume you're referring to a Swann model, in which case more detailed information is no doubt available from them.

If video quality is too poor to discern it then the only feasible way would be to grab a still image (I assume the car is moving) and then process it within an imaging program. Tweaking the histogram/contrast may make it possible to read, at least partially. It's possible to reduce compression artifacts slightly which may help.

It would be possible to couple it (into a satellite cable) using a 1.2GHz video transmitter which is readily available (probably some 900MHz transmitters too if you're in the USA). This would need to be loosely coupled (as in wrapping the output around the coaxial cable) or more directly by using a satellite splitter which provides DC isolation. However, this isn't really a practical solution as it's likely to interfere with existing satellite signals (sharing the same I.F. range) and your satellite receiver is probably digital whereas the 1.2GHz signal will be FM analogue.

> I don't think it will burst into flames or anything like that If the power connections are shorted then that may possibly happen. The construction of the batteries are usually quite robust and would require considerable effort to break apart. > how much energy do most wireless CMOS cams spend as a general rule It depends on the model obviously but on average about 50ma. However once you add infra-red LEDs and a transmitter it's going to be about 250ma. The infra-red LEDs should have a sensor so that they're only working when light becomes low enough, this should considerably extend battery life. > would I have to get a 30 Ah battery if I want to be able to recharge once a week? For 200ma that should be almost adequate. If you bear in mind that the duty cycle of the IR LEDs will not be 100% then it may well be more than adequate. It's better to have two batteries and simply exchange them rather than the one and having to wait for it to recharge. Note that sealed lead-acid batteries should NOT be left in a state of discharge for long, otherwise they'll become useless. > motion detecting" mechanism doesn't seem to be related to battery life If done at source, say, using a PIR alarm it can save consumption but then you'll have to factor in the consumption of the PIR and associated circuitry. Having the camera switch on only when the PIR is activated can be problematic, as a camera and transmitter will often require a few seconds to give a stable picture. As for extending microwave frequency range then rather than just transmitting higher power, it's better to use a high gain receive aerial with a pre-amp mounted directly to the aerial, which reduces coaxial cable losses which are substantial at microwave frequencies. To give you some idea of the advantage of line-of-sight, law enforcement helicopters often use just 500mW but have a range of around 50 miles.

Constant flickering at a constant rate? The PSU will be fine with 220V input (BTW, it's 50Hz, not 50GHz!) It may well be caused by a poor PSU, is it a regulated output? It could also be down to video cable routing (does it run alongside other cables?), or the connection itself.

Other factors to consider with wireless range are the frequency used, gain of the antennae and if the receiving location has windows. Obviously line of sight is preferable but you can still often get acceptable results because microwave frequencies will actually 'bounce' around. Also bear in mind that if using the 2.4GHz spectrum you may encounter interference from WLANs and microwave ovens.

> It's probably less than 20 meters. This means a wireless link can be low power which is good. > With low resolution it would be enough Therefore a CMOS camera will be adequate, this again is good as power consumption is lower than for a CCD camera. > how can I calculate, given the specs of a lead-acid battery and given the specs of a device, how much it's going to last? You should divide the Ah rating of the battery by the current consumption of the devices used. E.g. a 10Ah battery with a total current being used of 500mA should theoretically give twenty hours. Actually for a useable voltage it will be slightly less than that, perhaps 19 hours. > And how long does it take for one of these batteries to get charged? It depends on the Ah rating (the current capacity) of the battery and the charge rate of the charger used. Note that sealed lead-acid batteries require constant voltage chargers, so you can't just use a typical car battery charger.

What's the distance between the target location and the 'control' location? What resolution images would you require? I also suggest using a sealed lead-acid battery, which could be buried to make it more covert.

BTW, I'm struggling to remember my own results when looking at LCD displays using cameras with infra-red sensitivity but I have a recollection that it can give confusing results (i.e. the opaqueness of the display may differ from that seen with visible light). I'm sure others here will be able to confirm/deny this, but I thought I should mention it anyway.

When experimenting with CCTV cameras in the past I've found no problem focussing up very close using standard 4-8mm lens, the ability to adjust the back focus (if available) certainly makes it easier with no real need for a macro lens (at least in my uses). I'm assuming that image quality itself isn't that important, just the ability to read the gauge.

If light is indeed zero then you will see nothing, LCDs require ambient light to be visible. A backlight will obviously give results although a single LED mounted in front may well be adequate.

Well obviously reformatting would be required if it's formatted in a format your OS doesn't support. As for stressing hard drives to the same level as for a DVR, there are programs available that will do stress/burn-in tests on a PC.

It was brand new from Maplin Electronics but discounted as it was old stock. A (supposedly) cloned remote control for it was for sale online from a third party, which I bought but it failed to work. My enquiry to Swann was more broadly questioned - just asking if they had any remote code for their products which would be suitable for use in a universal remote. I wasn't too suprised I didn't get a reply from either them or Safe-Core. Obviously tracking down a user willing to help in that way is extremely, er, remote but I was hoping there would be some generic/OEM names cited that I could try.

I'm curious as to which makes are effectively just the same but rebadged? For example, my Safe-Core DVR400M appears to be almost identical to a Swann model.

I bought one recently but although it appears to have this facility there was no infra-red remote control supplied. I did a search and found one that was claimed to work on it but it didn't. I'd like to know if indeed anyone has a DVR400M along with a remote control and would very much like to know if I can use a universal remote for this. I've searched on the usual Vivanco database, but cannot find an entry (with codes) for Safe-Core. Can anyone please assist with this? TIA, Gary

lol Preferably I'd want someone with an oscilloscope to send me the PWM rate and datagrams...

Thanks for the reply, I was pretty sure that was the case with just cosmetic changes and firmware editing being the differences. Part of the reason for my question is related to another query I have made here regarding obtaining a remote for my Safe-Core PVR. Neither Safe-Core or Swann responded to my emails on this, so it would be nice to know if there's a known remote control code sequence (for universal remotes) that could be used from another manufacturer.

As mentioned, the hard drive is probably the most likely culprit. You can of course test it in a PC first rather than buying another one just to prove it. You might want to check for any firmware updates just in case it is a known bug.

H.264 should in theory give better results but that may depend on the actual encoder used. Its advantage of smaller files is nothing special though given that high capacity hard drives are cheap. I would consider the main features to consider are recorded line resolution and frame rate per camera, as most of the compression standards you mention are adequate for CCTV video. Providing there are no known reliability or ergonomic issues with a cheaper generic model, then I'd just go for the best specification at the price I can afford.

I may be wrong but I think it's to indicate that the hard drive is almost full. Naturally if you've set it to overwrite previous footage then this can just be ignored.