Wireless A/V FAQ


1. What does "line of sight" range mean- and what kind of range can I realistically expect?

2. I've seen 434 / 900 MHz, 2.4 and 5.8 GHz units- which frequency do I choose?

3. Why is the directional aspect of antennas SO IMPORTANT?

4. Are Eyespyvideo.com transmitters more powerful or better than others I've seen advertised?

5. What interference sources and barriers are the best & worst?

6. What is a "high gain antenna" and how effective are they?

7. How many wireless transmitters/ cameras can I operate at one time?

8. If I use more than one transmitter, will I need more than one receiver?

9. Are there hardwired solutions available which may be more beneficial than wireless?

10. Can you guarantee that your equipment will work in my desired situation?

Q1: What does "line of sight" range mean- and what kind of range can I realistically expect?

A1: The "up to" range, whether realistic or exaggerated- as found on so many sites- is always going to be based on maximum line of sight conditions. The term "line of sight" refers to stationary performancewith zero barriers and zero interference (electrical, radio, electromagnetic.... and even atmospheric and geological!), with both antennas at same height (at least 6 ft. and preferably MUCH higher to avoid trees, people, buildings, etc.).
As far as the range you can expect, it will be largely determined by the following factors:
1. Frequency selection.
2. RF output power of transmitter, which is usually measured in milliwatts (mW) or watts (W) for civilian/ non-commercial purposes. Broadcasting radio and television stations may even generate megawatt power from their transmitters.
3. dB (decibel) sensitivity or gain of BOTH transmitter and receiver components- as well as the potential gain of auxiliary antenna(s) and/ or external amplifiers.
4. External interference source(s). Generally, the worst kind of interference a RF radio signal may encounter is another nearby radio signal operating at or close to its own frequency in the RF spectrum. These 2 (or more) signals then "compete" for use of this frequency. If there is any 'winner', it will always be the stronger signal present. For example, a microwave oven is essentially an extremely powerful microwave transmitter tuned to the 2.4GHz frequency range. Read questions below for more insight into inteference issues. We often employ shielding techniques in video wiring (esp. for long runs) to keep radio signals OUT of the wire, to keep it from acting as an antenna.
5. Barrier(s) such as walls, buildings, vehicles, trees and even people. A wall is not just a wall when it comes to radio transmission and penetration. Materials, densities, etc. can range greatly even in similar looking walls and floors. Radio signals are subject to being absorbed- which diminishes signal strength- as well as reflected or bounced in different directions- including back to the source. A good example of reflection is when you see a 'ghosting' effect on a particular television channel- where you see the same signal multiple times on the screen. This is caused by part of the TV station's signal coming straight through to the antenna, and other part(s) of the signal reaching the antenna after being reflected off another barrier.
The reason you'll find your car stereo antenna on the OUTSIDE of the vehicle rather than the inside, as the automobile is a giant metal box which acts as a shield to RF radio transmission/ reception. A propagated radio signal travels along a wave moving at the speed of light. When it encounters a barrier, some of the signal penetrates the barrier while another part may be reflected in another direction.
No matter what, all customers should go into wireless technology with eyes open, realizing that- truly amazing as it is- that it's not perfect or magic. And even though it may well provide near perfect performance for a given application, these types of systems are not multimillion dollar network broadcasting licensed mobile satellite uplinks (which, by the way- can have their share of problems as well). And though each item on this site has been hand selected and tested for practical use in the 'real world', no wireless link made will provide as reliable performance as obtained with a camera connected directly to a recorder or monitor (hardwired). You simply cannot expect wireless equipment to do what it is not capable of- like penetrating multiple buildings or wooded conditions. The best you can do is to take time with your homework and then invest in the very best and most powerful equipment your budget will allow. Here's where we have good news for you on both points- we carry only the most powerful equipment available & at a (usually) much lower cost than the competition charges for inferior equipment. We've seen our equipment out there for up to FIVE or TEN TIMES our price!
Back to top-->

Q2: I've seen 434 MHz, 900 MHz, 2.4 GHz and 5.8GHz units- which frequency should I choose?

A2: First of all, there are several other considerations to make before frequency selection. All these frequencies are considered part of the radio frequency (or RF) spectrum. As far as 2.4 ghz (or 2,400 megahertz) signals in motion- it's a little hard to explain. When both points are stationary, you'll generally have a crystal clear signal (depending, of course- on interference and barriers). As one or both of the points are in motion, there can be an unusually large amount of signal breakup. Unlike "snow" received from lower frequency units, you get momentary pops inbetween clear signals. Higher frequency signals are more directional by nature. By using the two receivers (one with built in omnidirectional antenna & the other with a high gain directional antenna), some normal interference will be stabilized.
Essentially, lower UHF frequencies like 434 and 900 megahertz are better for those applications where motion exists in one or both links (i.e. body worn or mobile applications). Lower frequencies also TEND to provide better barrier penetration. The audio / video quality is otherwise identical.
The TX-5 and TX-5A (434 MHz UHF) are both excellent transmitters- but 434 MHz can be a little tricky in the "real world". The sensitivity of the receiver and the sensitivity- or gain ability of a properly tuned frequency antenna used will make all the difference in terms of the signal quality, barrier penetration and range performance. Expected video quality can range from marginal or even poor to excellent, depending on the quality of the tuner and antenna within the UHF band. *NOTE: Most consumer level VCRs and televisions are known for having weak built-in UHF band tuners. And high gain antennas (see below) are extremely hard to find tuned into this frequency range.
For that reason, most would-be users of UHF 434 are ideally recommended to use our 900 MHz with matching receiver instead. Again, however, lower frequency (900) units will provide a MUCH more stable signal than microwave links where transmitters and/ or receivers are in motion. For stationary links, low or high frequencies are of little consequence- but the higher powered higher frequency units are typically recommended as they tend to have directional antennas built in.
5.8GHz transmitters are the newest entry into the consumer and commercially available frequencies and have a couple of major advantanges going for them. First of all, there is not that much equipment out there using this frequency- and it's not being used by all levels of consumer-level equipment. Also, you have a ten channel selection, allowing you to fairly easily avoid the rare signal(s) which may be close enough to cause a problem.
Back to top-->

Q3: Why is the directional aspect of antennas SO IMPORTANT?

A3: There are a WIDE variety of antennas available, each designed for given purpose of sending or receiving a radio signal. Depending on the engineering design. Bigger is not always better (since there are some very poorly designed)- but it tends to be. There are exotic types and names, like 'conical', 'horn' and 'helical phase'. But for general video surveillance and most uses, the following are the major types of antennas:
1. Dipole / whip. OMNIDIRECTIONAL. These usually look like a stick and may be long or short. 99% of car radio antennas are dipole whip type, as are cordless phones, cell phones, walkie-talkies, etc.. Their transmitting / receving strength generally relates to size.
2. Patch / panel. DIRECTIONAL. Also referred to as 'circular polarizing patch' and are generally found with high frequency (microwave) systems. We offer some 2.4 GHz antennas in this variety.
3. Yagi. DIRECTIONAL. These are often identified as 'several antennas within an antenna' because of the number of elements (or metal bars) in the total array. Not all frequencies can be used with a yagi antenna.
4. Parabolic / dish. DIRECTIONAL. These are most commonly seen as the satellite television antennas on every other house. Generally speaking- again, the larger the antenna... the better. However, in practical terms- not every location is a good one for having a giant (1 meter + diameter) grid dish antenna!
As you can see, antennas are generally referred to as directional or omindirectional. Omni directional means that the antenna's power is radiating in all directions. The advantage to these is that they don't rely on precise situation of antennas, so are more appropriate for moving/ mobile uses. The drawback is that the same frequency and output power system will go several times further when the same signal is concentrated into a narrow directional beam.
This is why a directional antenna configuration of a 100 milliwatt system may exceed the range obtained by a 500 milliwatt power system outfitted with omnidirectional ones. Omnidirectional and directional antennas may be used together. The best way for a signal to be transmitted and received, regardless of frequency, is with both sides using directional antennas which are properly positioned for optimum performance.
Back to top-->

Q4: Are eyespyvideo transmitters more powerful or better than others I've seen advertised?

A4: In most cases- YES! However, right off the bat- there are several considerations to make regarding this topic. When it comes to most transmitters we've seen out there on the net- profit over performance value seems to be the primary consideration to most sellers. Not to be confused with most toys with their low power output and often heavily exaggerated claims of range / distance ability, our A/V systems have the latest built in surface mount technology. Also, our specifications for output power are based on AVERAGE RF output power- not it's peak. Our 500mW TX-9500 and THX-9100 units have an average RF output of over 480 milliwatts, with a PEAK power closer to 700mW. However, we don't advertise it as 700mW power!
Our 2.4, 900 and 5.8 systems use FM synthesized signals, featuring more stability and higher resolution capabilities than the typically found AM modulated units. Crystal IC controlled transmitters with phase loop lock receivers provide 'drift-free' signal performance. Patented signal technology tends to make our units head and shoulders above most of our competition. Though, again- please realize that RF wireless technology is not magic.
Back to top-->

Q5: What interference sources and barriers are the best & worst?

A5: When it comes to wireless, there really is no such thing as a 'good' barrier or interference source- but there are definitely some that are much worse than others. As far as interference goes- it usually is the result of alternate equipment which is locally operating in the same frequency range. Most complaints seem to be about 2.4GHz systems, There are SO MANY types of devices sharing a limited amount of radio spectrum in what is referred to as the ISM (industrial, scientific, medical) BAND. Most 2.4GHz devices operate in the ISM band. Cordless telephone equipment, wireless LAN networking and microwave ovens when operating around 2.4GHz video may cause big problems in performance ability. Conversely, if you are using a 900 megahertz cordless phone around our 900 MHz wireless video, you may experience interference in either the video or the telephone- or both. Back to top-->

Q6: What is a "high gain antenna" and how effective are they?

A6: A high gain antenna is a specially engineered antenna which is 'tuned' to a particular frequency range within a given section of the RF (radio frequency) spectrum. They are used to increase the effectiveness of an existing transmitter or receiver & are extremely effective when used properly. These can greatly increase the reception range of any of our products. Most antennas you'll see are DIPOLE type antennas. These are generally seen as a stick/ whip shape and are generally not referred to as 'high gain'. Eyespyvideo.com does carry several types of high gain antennas:
Flat panel 'circular polarizing patch' models for 2.4 gigahertz.
Yagi for 900 megahertz and 2.4GHz.
Parabolic antennas are available for the 2.4GHz and 5.8GHz units.
PLEASE NOTE: High gain antenna systems are almost exclusively DIRECTIONAL in nature. That means that the video link will rely on the transmitter antenna and the receiver antenna to be situated (or pointed) DIRECTLY at each other. We do not carry high gain tuners or antennas for 434 MHz equipment as amplified/ powered UHF antennas are rare in this frequency range.
ALSO NOTE: High gain antenna systems WILL NOT eliminate or improve a signal in the presence of nearby competing RF interference. In fact, quite the reverse may occur as the interference itself may be increased with the rest of the signal!

Q7: How many wireless transmitters/ cameras can I operate or monitor at one time?

A7: Theoretically, with our presently available equipment, you could operate 16 transmitters at the same time- ten @ 5.8GHz, four @ 2.4ghz, one @ 900mhz and one @ 434 mhz. Also, there are ways to send multiple video signals over one radio signal, provided the signals are multiplexed (or split) going into the transmitter and then de-multiplexed out of the receiver. This gets very acomplicated and is subject to a number of limitations and cautions.
For more answers about multiple camera systems, please click here refer to the multiple camera FAQ answer page.
Back to top-->

Q8: If I use more than one transmitter, will I need more than one receiver?

A8: It depends. For multiple channel transmitters operating at the same time (and for the same frequency), you may choose to use a single receiver and manually switch between channels to view and/or record activity. Our RX-910 and TXRX-1WW receivers are manually selectable, but also feature "auto-sequential switching" ability, which means that the receiver will tune in to a particular channel for a given period of time (referred to as 'dwell'). However, should you wish to monitor all signals simultaneously (such as on a quad processor or multiplexing DVR)- you will require a matching receiver for each transmitter. Back to top-->

Q9: Are there hardwired solutions available which may be more beneficial than wireless?

A9: Just because you have an extended distance to cover, you may not want to automatically assume that wireless is the only way to go. Not only should the potentials for interference and barriers be considered, but also for the ability of signal(s) to be intercepted or even jammed from external equipment.
Even hardwired installations can be prone to interference. Why? Because a video cable or wire is essentially a long piece of metal which can tend to act as a natural antenna for signals
If you only require 100 to 150 feet, usually a simple video/ power cable like our VP series extension cables. For really long runs, use of baluns / modulator- demodulator equipment is necessary. We have inexpensive units available which can send high quality video signals almost a mile over even unshielded 'twisted pair' (i.e. category 5 CAT-5) cable. Please click here to view hardwired extension cable solutions.
Back to top-->

Q10: Can you guarantee that your equipment will work in my desired situation?

A10: No- not at all. Due to the reasons mentioned at the top of this page- there are simply too many variable factors which may impede what you'll call "desired performance". Therefore, it is recommended that you do your homework & purchase the best equipment you can attain. For larger projects, start small and see for yourself with real field testing to decide whether or not more powerful wireless links will be beneficial to your goals. It's not going to provide an ideal solution for everyone's situation and that's just a realistic as it gets. That's not meant to scare away potential customers who may be wary after having seen some of the JUNK floating around out there. Our wireless equipment is field-tested and has been pleasing customers for up to several years now. We supply some of the most advanced users of wireless RF products. Back to top-->