Since the timing accuracy in a CDMA-synchronized clock varies, why is the frequency so stable?
Unlike the timing outputs, the 10 MHz frequency output is not affected by propagation delay. Since both the basestation and the EndRun unit are stationary (they don't move in relation to each other) the frequency is extremely accurate, to parts in 10 to the 12th over 24-hour averaging times. On rare occasions, a basestation might experience a GPS outage, as when the GPS antenna is damaged. Under these conditions the basestation's GPS receiver would go into a holdover mode and its frequency could drift up to about a part in 10 to the 10th over 24 hours. An outage is rare, and one lasting
If the CDMA signal level is weak, does that affect the timing accuracy?
No. If the unit is able to acquire and decode the data, the accuracy is just as good as with a strong signal level. There is no gradual degradation of timing accuracy. The time data encoding scheme ensures that if the data is decodable, it will be valid.
The unit is able to receive and decode data even with very poor signal levels. It only has to be able to decode one low-speed CDMA channel, unlike cell phones that need to decode multiple high-speed data channels.
Why does the timing accuracy on a CDMA-synchronized clock vary?
CDMA basestation transmissions must be synchronous with UTC to within 10 microseconds, typically much better - less than 1 microsecond. This variation is due to the possibility that a basestation might have a GPS outage, a rare occurrence. Under these conditions the basestation must stay within 10 microseconds of UTC for as long as 24 hours. This ensures the smooth operation of the CDMA telecommunications system.
Do I set my calibration delay to positive or negative to compensate for the antenna cable?
The answer is positive because there is a delay between the antenna and the receiver.
Think about it like this: The antenna receives the time data x nanoseconds before the receiver. Therefore, the receiver is behind the antenna by x nanoseconds. By entering a positive delay, the clock will be advanced x nanoseconds to compensate.
Do I have to pay a monthly cell phone service fee to use your CDMA products?
No. Our CDMA-synchronized products merely receive the timing signals that are freely transmitted from basestations and which are used by the mobile handsets for synchronization. Since our units only receive the timing data and do not transmit any information, no subscriber fee is required to use our instruments.
How do I know if I am in a CDMA coverage area?
CDMA coverage is throughout the USA, China, Korea, India, Japan and elsewhere. The best way to know if you have CDMA coverage is to find someone with a CDMA cellular or PCS phone and see if it indicates any signal level at all. Our products work in very poor signal level conditions.
If you are unsure that you have the appropriate CDMA coverage contact us. Also, since we offer a 60-Day Money-Back Guarantee there is no risk in trying it out. We have shipped thousands of units throughout the world and our return rate has been less than 1%.
Do your CDMA products work with PCS or cellular and what is the difference?
The difference between PCS and cellular is the frequency band. PCS frequencies are at 1960 MHz and cellular frequencies are at 881 MHz. All our current CDMA-synchronized products use a dual-band CDMA receiver and can receive either cellular or PCS signals. Some of our earlier products use CDMA at cellular frequencies only.
How much longer will CDMA be around?
In the United States, we expect CDMA service to sunset by the end of 2022. For background and details, click here.
