Cobra XRS 9440 will not detect police radar. Does not alert when I drive by a police car. How can I fix this problem? Is there a way to change the settings so that I can be alerted when there is police nearby? I read the instructions manual and could not find any helpful info.

Press and hold Dim and City buttons for four seconds
Voice Response with say, "Pop On" or "Pop Off" Tone Response will be, Pop On = Two Beeps, Pop Off = One Beep
You can find the full manual here:
http://www.manualnguide.com/manual/cobra-xrs-878-manual/

http://www.cobra.com/pages/product-manuals#Radar Detectors

That's the MFG link. I found your unit but they are doing updates to their system & will be back up and running shortly. Hope this helps

Radars are like just about anything else you buy these days, you get what you pay for. If you want a cheap but most reliable for the price I would suggest the Whistler XTR-695 *est. price 150 bucks. Although many detectors are prone to being detected by radar detectors (used by law enforcement) this one is a little more likely. So if your state has a ban on radars I wouldnt buy. As far as distance in signal pick up the Valentine One I would go with *est.price400 bucks.

The detector will only work if there is a signal transmitting at the time. Depeding on what country you are in, police usually don't activate their radars three minuites before they register your speed. These are more meant for stationary speed cameras than hand-held ones.

5amp...

POP is a type of radar mode which only a couple of radar guns have. In essence, radar gun in POP mode emits an extremely brief signal to measure a car's speed. This brief signal lasts for less than 1/5 of a second. POP mode can not legally be used to write speeding tickets since it is not as accurate as the radar gun's normal operating modes, and since POP mode provides absolutely no radar tracking history.

Most people turn off POP mode in their radar detector's options since POP radar is very rarely encountered and since users experience excessive false alerts with POP turned on.

Spectre refers to the Spectre radar detector detector (RDD) which police use to locate drivers who are using radar detectors. The current Spectre models in use by law enforcement are the Spectre III and IV models. Some Cobra radar detectors claim to be able to detect the Spectre I. This is of no value since all Spectre I RDDs have been upgraded to later Spectre models which Cobra radar detectors can not detect. In short, turn Spectre detection off since this feature is a needless source of false alerts.

These are just the frequency ranges, or "bands" that your detector is detecting the frequencies...

X, K, Ka (Kappa-Alpha) are different bands of frequencies.

The x-band is the considered a "trash band". It picks up things like automatic doors at supermarkets and such. About every radar detector made has an X band for non-police radar. There is no way to turn this band off on the XRS-757.

Holding down the dim button for 2 seconds turns the V alert on/off
Holding down the city button for 2 seconds turns the Spectra on/off
Holding both city and dim together for 2 seconds turns K and Ku band on/off.

X, K, and Ka Superwide are the radar bands that are used by police radar guns. X band was the first band used for by radar guns, but is now the least used. All radar detectors that we carry detect all 3 of these bands.