VS FAQs 3

How does Bluetooth and Wi-Fi interfere with my Video Senders? How do I recognise it?

Bluetooth and Wi-Fi computer wireless networks also use the 2.4 GHz band to operate in. There is therefore the possibility of interference if any of these devices are operating nearby.

Once you have seen Wi-Fi interference you will recognise it in the future. It produces moving horizontal white bands moving up or down the picture. They will get either better or worse when you change the Video Sender channel. This type of interference usually spans about four Video Sender channels. On a five channel system either channel 1 or 5 will usually be sufficiently clear to give acceptable results. With a sixteen channel system, channel 8 should be completely free from both Bluetooth and Wi-Fi.

Try temporarily removing the Transmitter aerial, which will make the interference much worse. It is then much easier to tell which channel is best. It will also allow you to identify the type of interference more readily. Don't forget to replace the Transmitter aerial when you have decided on the best channel!

I've heard about "reverse polarity" damage - what is it and how can I avoid it?

Most electronic equipment is designed to be run on a range of voltages supplied with the correct polarity, ie: +ve and -ve the correct way round. This is not normally a problem if you use the manufacturer's pre-wired cables and power supplies. However, the ubiquitous 2.1mm coaxial power plugs that abound on equipment today can prove to be a problem.

PAG were one of the first to use this plug and they chose to wire it centre pin -ve. After very many years and thousands of units sold, this obviously cannot now be changed. Unfortunately though, most newer units using this plug are centre pin +ve. It is very tempting if you have a mains power supply that is 12 volt with a 2.1mm plug on the end to plug it into a film device that expects to see the PAG standard. This often happens to LCD Monitors such as Panasonic's 7" widescreen. Sadly, this will blow the internal board fuse, which is a job for an experienced technician.

A word of warning: if you come across the little Optex 2" LCD Monitor - this is actually wired reverse polarity with its Hirose plug!!! Pins 1 and 4 are wired reverse to the industry standard that everyone else abides by. Plugging in a standard 12v Hirose 4 pin supply will fry it - good and proper, with lots of smoke! The protection fuse only protects the 2.1mm jack, not the reverse wired Hirose socket. YOU HAVE BEEN WARNED!

Will reverse polarity damage Black Box Video's units?

Virtually all Black Box Video's units are protected against accidental reverse polarity - they simply won't work, then when correct polarity is applied they carry on without damage.

It is quite a good way to check a suspect supply or lead as there will be no damage to the Video Sender units.

Our Video Sender Transmitter is ideal as the green LED gives an instant check if the supply is OK. Also, it will withstand 9-36 volts without damage. An exception to this is The Stamp as it has built-in leads and no reverse polarity protection.

The Panasonic 7" LCD Monitor (which used to be supplied with The Package before it became obsolete) will definitely not withstand reverse polarity so be extra careful when powering this item. We can repair it for you if this does happen, but it will cost you £50!

What about the DataVideo Monitor that now comes with both The Package and The Thrifty Package? Is that likely to have a problem with reverse polarity?

Unfortunately, it is possible to plug a PAG NP1 shoe via its BP90 connector directly into the DataVideo Monitor, which would reverse polarity the Monitor. Sadly, there is nothing we can do about that - it is a legacy problem.

The DataVideo Monitor has some protection against reverse polarity so is unlikely to be damaged by accidentally connecting back to front from a 12 volt source. However, I don't advice deliberately trying this, especially with a freshly charged lithium battery which can reach almost 17 volts! You just might run out of luck!

As from May 2008 our Remote Switch will be fitted with a protection diode to prevent damage if it is inadvertently connected incorrectly. The polarity will, from now on, be changed to be centre pin positive so that the whole package can be safely powered by the mains unit that comes with the DataVideo Monitor.

My Panasonic 7" LCD Monitor seems very dim, even on maximum brightness. How can I improve this?

Chances are that the monitor brightness is set to "Automatic" in Menu 1. There is a sensor on the front panel that is covered in the Kata bag and this will set the brightness to minimum. Access Menu 1 and set the brightness control to "Manual". This will fix the problem.

The picture seems to have lost Sync on my Panasonic 7" LCD Monitor - how? and what should I do?

If you have no locked video, just lines scrolling at about 45 degrees, this is usually caused by the video ground track on the Panasonic's PCB board having burned out. This is caused by a faulty power plug which has a short from positive to the case of the pug - usually a home-made HRS4M lead. This makes the think video ground track burn out like a fuse. We can repair this for you, but first you must find the faulty lead or it will happen again!

Can I use high and low power Video Sender units together?

It is not advisable to mix high and low power five channel units on the same location. However, the high power Transmitter can swamp the lower power units. If using sixteen channel units you can mix high and low power if you choose frequencies that are far away from each other as possible. See the question below

Can you clarify the range of High Power Video Sender units in metres (both direct line of sight and within a built-up environment)? And what difference does the Yagi aerial make?

The expected range - line of sight - of the High Power Video Senders would be approximately 300 metres. However, using the Yagi aerial outside, the range would increase to approximately 700 metres line of sight.

The Yagi aerial is not really intended for indoor use, although this does not prevent you experimenting - but the results would be highly unpredictable. See the Aerials and Leads page for more details of the Yagi.

The expected range in a built-up environment would be approximately 100 metres, but this is only a rough guide and it is partly dependent upon the construction of the buildings. There are also many other factors involved, such as whether there are human being present and if so, whether they are moving around, the presence of computers, the presence of mobile phones, etc. The list of "other factors" goes on and on!

How do I choose the most suitable and correct channel/frequency to use my Video Senders on?

Having the ability to choose from a range of channels with your Video Sender is increasingly important in an ever more congested radio spectrum.

Most domestic units have only four channels with an 18 MHz channel spacing. Our units have either 5 or 16 channels with a 14 MHz spacing.

Channel 1 is generally a common channel - ours is 2414.50 MHz and most manufacturers' units are close enough to exchange signals on this frequency. After Channel 1 the frequencies diverge more and more.

Channel 1 therefore tends to suffer more interference from other Video Sender units. However, Channel 5 suffers more from computer Wi-Fi and Bluetooth interference.

Simple advice, but it is always worth experimenting with different channels in any given location if you are suffering interference.

If you are using two or more Video Senders in the same location you need to go for the maximum channel spacing, subject to them both being interference free. At the very minimum you must have at least one guard channel - say, channels 1, 3 and 5, but not channels 2 and 3.

Our five channel units operate in the 2.4 GHz band, but our sixteen channel units go down into the 2.2 GHz band which completely clears Wi-Fi, Bluetooth, microwave ovens and most other senders. This is one of the great advantages of a sixteen channel system, even if you only use one channel it can rid you of troublesome interference.

It is worth pointing out that on the sixteen channel units the lowest frequency is Channel 8 at 2288.50 MHz. This is clear of virtually all interference at the moment. Channel 7 is the highest frequency at 2498.50 MHz.

On the five channel units there are only five valid channels, they are Channel 1 through to Channel 5. Although there are ten positions on the channel selector switch (0 to 9) and you will get pictures on channels other than 1 to 5, these are "ghost frequencies" and is is not advisable to use them. The channel numbers 1 to 5 on a five channel unit are compatible with channel numbers 1 to 5 on the sixteen channel units.

NOTE: If you select any channel other than Channels 1 to 5 on a five channel unit, you will not get a picture if you use it with a sixteen channel unit. The reason being the five channel units have a ten position switch is simply that we cannot buy five position switches!

The sixteen channel select switches use Hex notation, ie: A to F for Channels 10 to 16. The switches come like that! The 16 Channel Diversity Receiver has digital channel display so we were able to simply number the channels 1 to 16, ie: Channel 10 = A, Channel 16 = 0.

Confused? Then just buy The Stamp - it has only got one channel!

When selecting a suitable frequency on the sixteen channel units it is worth consulting the frequency chart that came with your units. To keep channel number compatibility with the five channel units, the sixteen channel units extend channels both above and below the five channel frequencies which gives rise to the apparent anomaly that Channels 7 and 8 are furthest apart, not closest as you might at first expect! If in doubt check the chart.

Can I see the frequency chart here on the Black Box Video website?

Sure - have a look here for the

My Monitor doesn't support audio, but I need sound - how can I get sound using your Video Sender units?

If you require sound with your Video Sender units when your monitor does not support audio, we can now offer our new Micro Headphone Amplifier - see here for details

What is the legal situation regarding using Black Box Video's High Power Video Sender units?

Our High Power Video Sender Transmitters are not yet licensable in the UK. However, regulations change all the time - both our 433 MHz Time Code Transmitter and 863 MHz Foldback units have benefited from 20 times and 8 times power increases respectively due to legislation changes.

There are many places in the world where higher power units ARE legal - Germany to name just one. You are unlikely to cause any problems in the wastes of Alaska or the middle of the Sahara Desert either. So, if you wish to remain strictly legal where higher powers are not allowed, we can supply an attenuator which screws in-line with the Transmitter aerial and reduces the radiated power to within the legal limit for UK operation.

You keep mentioning the Panasonic and Roadstar Monitors - but I thought they were obsolete? Why do you keep mentioning them?

They are now only mentioned because so many of our customers have these units and may still seek advice and information, which we try to continue to provide.