CCS/CC430F5137: CC430F5137

Hello,

I've assigned an expert to look into your issue.

Thanks,

Alexis

Hi,

What is the RF level you are expecting from VHF Transmitter?

Do you have any Bandpass Filter on the Front-End to suppress Unwanted Signals?

Do you put any RF Shield on the device?  RF Shield protects from very strong RF signals.

Could you please post your Schematic in PDF for Review?

Thanks,

PM

Hi,

It has been a while and I don't see any reply from you. So, I am going close this thread.

If you need any further help, you can reopen.

Thanks,

PM

PM said:

Do you have any Bandpass Filter on the Front-End to suppress Unwanted Signals?

Greetings,

May my small group generally agree w/your assessment - yet add:     (one of our (outsider firm's) clients noted this - & requested)

• often there are 'RF null zones' - some (surprising close) to poster's board - and often (even) w/in the same room.    Poster must measure the RF signal level of the 'offender' and experiment to learn if a 'reduction in signal level' can be achieved (& maintained) via simple 'board relocation.'
• a Bandpass Filter was suggested - yet a 'Band Reject Filter' was surely implied.   (Such High 'Q' filters can be hugely successful - but likely require that the 'offender' (substantially) holds to frequency.)
• the 'RF Shield' cannot hurt - yet the design & emplacement of one, 'After the Fact' - is likely to present a challenge.    Thus - the 'earlier noted RF Reduction Techniques' should be employed first - adding the RF Shield (only) if still required.    (although should the board move (away from the null zone - or should the offending device 'raise power' - that shield (may) become necessary.)
• if there is a 'Fixed & Known' remote RF device being targeted - then the use of directional antennas - at both ends - also proves quite effective.    Further by boosting the strength of the desired 'received' signal - it may prove possible to 'Reduce the gain setting of poster's receiver' such that 'offending signals' may fall beneath the signal recognition threshold.    (one hopes)

As the 'Usage of RF Devices' grows - and 'most anything' may be encountered - perhaps it proves best to, 'Design for the (potential) worse case' - and at minimum - implement the 'pcb footprints and attachment points' for filters & protective RF Shielding components.   (these may be 'selectively' filled as/if (but likely when) needed...)

Thank you - we have long known (and purchased) from TDK.    (possibly you disagree w/our note of 'Band REJECT Filter' as opposed to 'Bandpass' Filter - otherwise we can't grasp your intent  ...  or as sometimes happens - you did not have time to 'read thru' the entirety of our posting.)

As our post noted - it was generated in response to one of our firm's (existing) clients - who asked that we review your posting - and (perhaps) add additional guides & items.   That was our intent - we have (some) experience & skill in the RF area...   (having designed such systems for the military, commercial broadcast & (most recently) autonomous vehicles...)

Greetings,

PM said:

If you think Band Reject Filter is more appropriate for your application then you can use band Reject filter. There is no harm in that.

Both will serve the same purpose. 

May we 'respectfully' disagree?     Both the poster here - and our 'forum reader/client' - had been bothered by a strong (local) VHF transmitter.    It is our (long experience) that a properly designed (Hi Q) 'Band REJECT Filter' provides superior rejection - when compared to the (earlier) proposed 'BPF.' 

In years past - operating as a radio ham - it was well noted that 'band-pass filters' would reject some 'TVI' (television interference) yet 'band Reject' (or band-stop filters) removed ALL of the interference.    Today it should be noted that highly selective 'Band Reject' filters are employed in 'multiple' (w/in quality RF devices) - strongly suggesting that their 'Band Pass' cousins (possibly enabling 'cost savings' due to 'just one filter') had proved 'unable' to replace the 'Band Reject versions' - demonstrating the 'extra rejection' which (only) the Band Reject Filter provides...

Such is 'Not at all unexpected' as the 'Band Reject Filter' targets a 'Substantially narrower frequency spectrum' (for rejection) thus is (almost) always - able to produce (far) greater  'targeted frequency'  signal rejection!    

Further - the use of a highly directional antenna - as our post (alone) noted - when & where appropriate - serves to 'best welcome' the desired signal - while 'opposing' the 'offender' - provided they are not (equally) in-line with the communication path.

Thank you as well - it is hoped that this 'back-forth' provides increased user insight into the 'Increasing demands' placed upon (most any) RF communication link.   

Again - the highly selective nature of the Band Reject Filter makes it 'unmatched' in rejecting 'Known, Fixed Frequency' offenders...