The hottest low-cost 24GHz wireless video monitori

The low-cost 2.4GHz wireless video monitoring device

recently visited the fry electronic store qb/t 1130 ⑼ 1 plastic right angle tearing performance experimental method near my home. When I walked to the DIY security products counter, I couldn't help but look at it for a while. In a row of self-service video surveillance products, a $99.99 surveillance kit attracted me

it seems a good deal to buy a set of 2.4GHz wireless audio/video monitoring equipment with two cameras and a base station equipment for $100, and each camera has a built-in ring infrared lighting device, which can work under almost no light conditions. The product is labeled with the trademark securityman nitecam2, and the manufacturer is AEE wireless company in Shenzhen, China

this product is easy to install. Each bullet camera with rain proof microphone can send audio and color video signals back to the base station by connecting the adapter to the AC power supply

the 2.4GHz ISM (industrial, scientific and medical) band used by the camera is set by the dip switch on the base station equipment. The base station equipment outputs video and mono audio composite signals through the RCA socket, which can be connected with any TV monitor. The effective distance given in the product description is 100 meters (clear visual distance transmission), but the distance that can be expected in actual use is much smaller

these two cameras are equipped with lens imager, microphone and RF signal transmission circuit, as well as a ring lighting device composed of multiple infrared LEDs, which can provide floodlighting invisible to human eyes for night use. According to AEE, the sensitivity is 7 meters when the minimum visible illumination is 5 lux or 0 lux (infrared illumination is activated)

to avoid mutual interference when multiple cameras are combined, the system provides four center frequencies (2414, 2432, 2450 or 2468mhz, with channel spacing of 18mhz) to transmit signals

omnivision ov7930 chip directly outputs 510 x 492 NTSC video signals. Its internal processing functions include original image acquisition, gain control, automatic color balance, NTSC format/conversion, etc

the electronic part of the camera includes bj8p153 8-bit MCU ROM controller of Shenzhen bojuxing Industrial Development Company (bjx) and rtc6701 CMOS 2.4GHz fm/fsk (frequency shift keying) transmitter of richwave company. Its RF output power is 10MW

although the richwave device supports the digital FSK function, the design only uses the relatively simple analog RF frequency modulation function in the device to complete the up conversion of the output signal of the omnivision image sensor NTSC. A protruding whip antenna mounted on the back of the camera is used to send RF signals

due to the use of FM scheme with low complexity, the system has weak protection against external interference in the increasingly crowded ISM band. Due to the lack of a very tight channel and the absence of more complex digital radio anti-interference measures such as error correction and/or coding, the design of securityman achieves a trade-off between complexity and performance. This pure simulation method ultimately wins with highly robust radio performance

the base station receiver antenna is an unbalanced dipole antenna (actually a stripped coaxial cable), which feeds signals to an obviously independent RF front end. The base station periodically checks each selected channel and changes the frequency of richwave rtc6503 frequency synthesizer with built-in VCO (voltage controlled oscillator), and the output of VCO is mixed with the received signal to form the 480mhz IF signal used in this design

audio and video signals must be further isolated after if output of mixer is filtered by surface acoustic wave (SAW) filter. The former is realized by the u2860-b Dual Channel FM Sound Demodulator of ATMEL company (temic). Since securityman adopts mono output, only one channel of u2860-b is needed

baseband composite video signal is sent by sl1461sa PLL FM demodulator of Zarlink company. The demodulator now seems to be an isolated device, because Zarlink sold its tuner and demodulator business to Intel, which no longer takes the device as the main product in the demodulator series

outside the a/v receiver circuit, the remaining main basic circuits are a 5V regulator (lm7805) and another 8-bit microcontroller. Elan microelectronics' em78p153 MCU contains its own disposable Prom of about 7kbits, dip switch channel selection, reset, RF mode, but because asbestos is carcinogenic, the tasks of block control and flash lamp control are completed by this 14 pin small device

this electronic design uses relatively cheap low integration devices, among which the CMOS sensor is undoubtedly the most complex IC device. I like the cast metal shell of the bullet camera very much. These enclosures are probably the most expensive part of the overall hardware material cost (certainly less than $50)

although this is a wireless system, I also appreciate the wired part of this hemispherical product. Although the product relies on RF for data link, the three AC adapters (one for the base station and the other two for the camera with only conventional accessories) are somewhat cumbersome. Hopefully, we can transmit audio/video signals wirelessly as easily as we can see in the design of securityman/aee