Filter
Top Products
41
12. What is DSSS？What is FHSS？And what are their differences？
Frequency-hopping spread-spectrum (FHSS) uses a narrowband carrier that changes
frequency in a pattern that is known to both transmitter and receiver. Properly synchronized,
the net effect is to maintain a single logical channel. To an unintended receiver, FHSS
appears to be short-duration impulse noise. Direct-sequence spread-spectrum (DSSS)
generates a redundant bit pattern for each bit to be transmitted. This bit pattern is called a
chip (or chipping code). The longer the chip is, the greater the probability that the original
data can be recovered. Even if one or more bits in the chip are damaged during transmission,
statistical techniques embedded in the radio can recover the original data without-the need
for retransmission. To an unintended receiver, DSSS appears as low power wideband noise
and is rejected (ignored) by most narrowband receivers.
13. What is Spread Spectrum？
Spread Spectrum technology is a wideband radio frequency technique developed by the
military for use in reliable, secure, mission-critical communication systems. It is designed to
trade off bandwidth efficiency for reliability, integrity, and security. In other words, more
bandwidth is consumed than in the case of narrowband transmission, but the trade off
produces a signal that is, in effect, louder and thus easier to detect, provided that the
receiver knows the parameters of the spread-spectrum signal being broadcast. If a receiver
is not tuned to the right frequency, a spread –spectrum signal looks like background noise.
There are two main alternatives, Direct Sequence Spread Spectrum (DSSS) and Frequency
Hopping Spread Spectrum (FHSS).
14. What is the maximum AP that can be detected?
Detector can detect up to 16 APs in a certain area.
For example, If there are 20 APs in an area, detector can only detect 16 APs.
15. What is the maximum detection distance?
200M ~ 250M in a open space.
16. How long it will take for the battery to be fully charged?
The charging period should be one hour or less, it depends on the left-over battery strength.
17. What is the battery life?
The battery contains recharging cycle up to 250 times.