两个问题？？？？？

zhd_1983

有两个问题，没解的开：
1.手机的TDD干扰，到底是217HZ干扰还是217HZ上负载的高频干扰到音频了？
2.手机天线的隔离度是怎么计算出来的，如双GSM手机，接受灵敏度-110DBM，发射最大功率30DBM，两天线之间的隔离度为什么只要15左右就ok了？

zhd_1983

没人解答啊。。。。。
自己顶个吧

coolbluetige

Not sure about the first question:
2) keep in mind that the TX/RX frequency is not the same, so the TX of GSM1 will not affect the RX of GSM2 as long as the max input level is below the RX can take. In other words, TX-RX SAW<Pin(max)LNA. The Antenna isolation maybe part of the antenna design spec not the radio it self.
JMHO

Rfantasy

what 's the "TX-RX SAWJMHO" mean?

BTW: I don't think it fit for every design.

GSM1 spurious emission in RX band --> A
A = [GSM2 sensitivity] - [C/I margin] + [Coupling loss between GSM1 & GSM2]
If Coupling loss=15, then A=-110 - 9 + 15 = -102 (dBm)

In fact, if you test "spurious emission in RX band", you can't get the value under -90dBm because the noise floor of Spectrum analyzer isn't low enough.  The -102dBm is unmeasured, but it's attainable by a TX SAW.

3GPP 51.010 think "A" value should be lower than -79dBm in GSM band.
It's based on: sensitivity = -104, couple loss = 34.5 (-104 - 9 + 34.5 = -78.5)
If "A" value = -80dBm. obviously, 15dB coupling loss cant meet the requirement.

In a word, If you cant get a better "A" value, you should increase your Coupling loss to meet your requirement.
[em01]