image frequency interference in bluetooth standard

[yubingz]

bluetooth interference 2009

Hi,

What's the "image frequency interference" and "Adjacent (1 MHz) interference to in-band image frequency" in bluetooth standards?

thanks!

Yubing

 

[vfone]

image frequency calculation

https://en.wikipedia.org/wiki/Image_frequency
https://en.wikipedia.org/wiki/Adjacent-channel_interference

 

[yubingz]

inband image frequency

Thanks!

But if i use low IF architecture, how image frequency go into the in-band?

thank you very much

 

[Mazz]

bluetooth in-band omage frequency

Imagine that you use a 1 MHz IF freq and you want to receive 2420 MHz.

You set your LO to 2421 MHz, for example.

If an interferer appears at 2422 MHz, it will be downcoverted to 1 MHz in the IF strip and will be rejected by the amount of image rejection (that is dominated by inaccuracy of I/Q LO phase).

I hope this is clear enough.

Max

 

[vfone]

what is an image frequency interference

In Low-IF receiver, generally the image frequency is converted to IF frequency nears the channel bandwidth. The image can be rejected at IF using a band-pass filter. If the IF represents the Adjacent Channel of the receiver you get maximum suppression of Adjacent Channel Interferer.

 

[yubingz]

bluetooth if frequency

Thanks Mazz! It's so clear.
But I still don't understand "Adjacent (1 MHz) interference to in-band image frequency" .