Installation Manual

F10 Installation Manual Rev. *60 54 of 71
• reducing the baseband gain during software processing (RX1 and/or RX2);
• reducing the hardware gain (RX1 Hardware/RX2 Hardware); and
• adjusting the receiver sampling hold off.
Digital readouts allow different points within the signal processing chain to be displayed through
the “C” view, or Set Filter Parameter Selection, which is a passive setting. This particular tool is
used only after first attempting to correct the environment.
Front end gain (RF section) is reduced when a sweeper or other external noise sources are very
close to the pedestal and the RX1 and RX2 adjustments do not lower the emission seen in the Set
Filter Parameter Selection.
RX1 and RX2 Hardware gain adjustment allows a variable setting of the front end gain replacing
the gain jumper. There is also a soft LED for each receiver, RX1 and RX2, to indicate saturation
in the front end. Between the RX Hardware gain adjustment and the soft LED, the CSE attempts
to find the point of saturation.
There are also internal noise problems (e.g., ringing) caused by board and antenna matching issues.
If the issue results from a low resonance close to the operating frequency range, this may be
resolved by increasing the gap (Sampling Holdoff) between transmit and receive cycles.
Note: For theory of operation and other detailed information on the different control settings, refer to the
NGL Installation Manual (CKP P/N 7360602).
The TR4215 board does not support inter-pedestal, Ethernet or modem functionality. Therefore,
settings for these features are not included in this document.
Noise Sources
There are generally two different types of noise sources our systems can encounter; asynchronous
and synchronous.
Asynchronous noise is random in nature and is found throughout the frame (signal and noise
channel) when certain devices are in close proximally. These sources may reduce detection and in
some cases, cause phantom alarms. Asynchronous noise sources could be any of the following:
1. CW Sweeper – These devices sweep throughout the detection band, degrading detection
performance, while causing false alarms. They usually have a constant linear sweep rate
(100Hz to 200Hz) with a certain high and low frequency range and a constant signal level.
2. Spiky Noise – This is usually from automatic door motors, (broken) lighting ballasts and
other pulse/listen systems that are not synchronized with the F10 system.
Synchronous noise is associated with items in close proximally to our system which resonate
during our transmission cycle and appear as a tag (with ring side down) to the detection system.
These present more of a false alarm threat when compared to asynchronous noise, especially if the
item is moving. They could also affect detection because of the complex mixing of the intended
tag signal and offending resonance. Synchronous noise sources could be any of the following:
1. Automatic Door Frames – In some cases metal doors will resonate and cause an emission
much like a tag ring down. When the door opens and closes, the background subtraction
(recall DMS) feature could be defeated, thus causing persistent false/phantom alarms.
2. Racks – Metal clothing racks will exhibit the same effects as door frames. When a rack is
moved, false alarms may occur.
Be aware that metal structures near the system may cause similar issues. Other sources of this type
noise could be merchandise close to, or passing through, our pedestals. In most cases merchandise
is most difficult to identify, because these items are meant to pass through the alarm region.