hoping with DDS and microcontroller

[Naveed_16]

hiz to all

can anyone tell me about the DDS interfaced with microcontroller?

i just need a system which can change its frequency based on control word generated by the Microntroller on DDS. Hop count per sec is not finalized yet. the frequency band will be VHF/UHF and 2.4ISM.

Waiting for help

 

[bigdogguru]

I'm afraid without stating the specific microcontroller and DDS utilized in your design meaningful advice will be limited.

 

[FvM]

I'm not aware of DDS chips working in the 2.4 GHz frequency range without upconversion or frequency multiplication. Also UHF capable DDS chips are quite expensive. Doesn't a synthesizer based generator serve your purposes?

 

[Naveed_16]

my project is just implementing hopping scenario. Im comfortable with PIC and arduino. i dont know which DDS chip can fulfil my need.

yes cost does matter.

my project include a microcontroller and frequency generator. microcontroller will write the control word to the generator chip. my hop rate is 1000hop/sec

if you know any alternative of frequency generator DDS, do share

 

[FvM]

Many synthesizer generators are capable of fast frequency hopping, e.g. radio transceiver chips. The detail specification matters however, step size as well as settling time.

 

[Naveed_16]

can i interface them with micrcontroller?

any company? any model?

i have no idea about all this

please specify something

 

[Naveed_16]

anyone can help me out in this problem????

 

[Dan Mills]

We cannot specify something unless you give us a proper spec to meet!
Tuning range, settling time, do you need AM? PM? I/Q modulation input? Phase noise requirements? ACPR? SFDR? The list goes on.

Analogue devices are the big dog when it comes to DDS (Most of which talk SPI or parallel if you need fast updates), but you will be looking to work at a suitable IF and them mix to final output (Certainally for 2.4G).

For low phase noise master oscilators the Crystek parts are quite nice, not Wenzel nice, but quite ok.

Minicircuits source the lazy mans mixers and filters, also gain blocks and circulators.

We cannot guess what your spec is, you have to tell us.

Regards, Dan.

 

[Naveed_16]

thanks for your kind response

i want to design a jammer application. there are two main terminologies of jamming. first is to use VCO with high sweep rate. the next one is to use DDS with FPGA for high sweep rate. i am looking to implement for the DDS base jammer. my first target is GSM and DCS. first i want to use DDS and microcontroller for this purpose. then in next step i will move to FPGA

so i need info about GSM and DCS DDS models

 

[Dan Mills]

That HAS to be illegal just about everywhere.

So you are looking for a chirped source (A sweep generator)?
It is a hidiously inefficient way to jam anything, especially if you know where the control channels are, but anyway, you can go after GSM much smarter then what you are proposing. .

The cheap thing to do is just an off the shelf VCO (Minicircuits) and a sawtooth generator (Opamp, 555, something like that), but if you must over think a sweep generator then the state of the art in DDS is output from near DC to somewhere around a GHz ( But you will need a 2.5GHz clock to pull that off). DC(almost) to ~400MHz is very mch easier, look to the AD9912 (Which also has a built in squarer, handy if the third, fifth or seventh harmonic can be engineered to be somewhere useful).

The other nice thing about the AD9912 is that it does programable sweeps as well as other waveforms built in, so you can program the thing in advance over an SPI link from your micro and then just send it a command to trigger a sweep.

Not a difficult thing to build, but as I say, illegal as hell and a chirp based jammer is not going to be particularly power efficient.

Regards, Dan.