hello
I have an AD9850 DDS module from ebay. the cheap one. I want to use it to generate a sine wave with frequency from 1-30MHZ. I have to write a technical spec or list of measurable for a project at college. my tutor is making this a little difficult for me as im a student and not qualified engineer. I don't know what kind of things to include in the list of measurable. I have looked at other low cost antenna analyzers to find their technical spec which is something like the following
frequency generation and control:
but I have a few problems.
the DDS module is the main one. comparing the frequency output with the display frequency. that shouldn't be too difficult. I would measure the frequency output and compare that by. output divided by display. I think this will give percentage error after x100.
then the quality of the sine wave, on here it says stability and spectral purity. I don't know how to measure these things, I found this and now don't know what im doing
I have read other things about mirror spurs and dB attenuation which is more confusing. this is an HNC course which is the equivalent of a first year degree (four years total).
I am whining some because I have very little knowledge of electronics. I completed a level 3 course and intermediate amateur radio license but this stuff is way above my head.
can anyone please give a suggestion about what I could look for to describe what I am going to measure and how I could do it. I did think that it would be a case of connecting an oscilloscope and looking at the sine wave over the frequency range and seeing if it drops off or changes shape at all because of distortion. I expect it to stay the same shape over the full range to 30 MHz because most other projects on the internet say that its that stable. so I don't know what to do!
any help would be great!
all the best
simon
I have an AD9850 DDS module from ebay. the cheap one. I want to use it to generate a sine wave with frequency from 1-30MHZ. I have to write a technical spec or list of measurable for a project at college. my tutor is making this a little difficult for me as im a student and not qualified engineer. I don't know what kind of things to include in the list of measurable. I have looked at other low cost antenna analyzers to find their technical spec which is something like the following
frequency generation and control:
- 1-60MHz
- source impedance 50 ohms
- stability +/- 100ppm
- spectral purity harmonic down >- TBD dB beyond 60MHz
- SWR 1.0 to 9.99
- impedance approx. 5 to 2000 ohms
- adjustable 2.0 volts pp (typ)
- external 13.8 to 19 volts DC, 500mA
- internal; 8xAAA 1000mAh NiMH cells
- charging time 12 hours (charge rate 0.1c)
- pushbuttons (5) mode, band, config, scan, up, down
- switch, power on
- RF out BNC
- usb mini b receptacle
- external power 2.1mm power jack (centre pin positive)
but I have a few problems.
the DDS module is the main one. comparing the frequency output with the display frequency. that shouldn't be too difficult. I would measure the frequency output and compare that by. output divided by display. I think this will give percentage error after x100.
then the quality of the sine wave, on here it says stability and spectral purity. I don't know how to measure these things, I found this and now don't know what im doing
I have read other things about mirror spurs and dB attenuation which is more confusing. this is an HNC course which is the equivalent of a first year degree (four years total).
I am whining some because I have very little knowledge of electronics. I completed a level 3 course and intermediate amateur radio license but this stuff is way above my head.
can anyone please give a suggestion about what I could look for to describe what I am going to measure and how I could do it. I did think that it would be a case of connecting an oscilloscope and looking at the sine wave over the frequency range and seeing if it drops off or changes shape at all because of distortion. I expect it to stay the same shape over the full range to 30 MHz because most other projects on the internet say that its that stable. so I don't know what to do!
any help would be great!
all the best
simon