Topics about radio telemetry, wireless transmission and reception

[Shey]

Kung mga radio enthusiast kayo or mahilig sa telemetry post kayo dito ng mga experiences ninyo or if you need help in design.

[Livelock]

Can anyone share some basic info on design of radio transmitter-receiver? I want to be able to create one by my own - if possible, pls. include piece parts(tipong electronic enthusiast) and short description of the function of each modules(in the PCBA).

Thanks!

[paranz]

Can anyone share some basic info on design of radio transmitter-receiver? I want to be able to create one by my own - if possible, pls. include piece parts(tipong electronic enthusiast) and short description of the function of each modules(in the PCBA).

Thanks!

Can anyone share some basic info on design of radio transmitter-receiver? I want to be able to create one by my own - if possible, pls. include piece parts(tipong electronic enthusiast) and short description of the function of each modules(in the PCBA).

Thanks!

As an ECE instructor, i believe mas madali maggawa ng FM or AM transmitters for students. you can design one using 3 or more transistors. Marami schematic sa internet pero wala calculations other than just descriptions.

You will need a thorough knowledge on transistor amplifiers (common-base, common-emmiter, voltage-followers, multitransistor amps), oscillator circuits, maybe power amplifiers, also freq. response of transistors.

you will need an oscilloscope, 2 channels preferably. If you are building an FM transmitter, you might need 100-Mhz oscilloscopes. kung am transmitter, gamitin mo 4-quadrant modulator IC para madali connected to a power amplifier.

[Livelock]

Thanks you, Sir!

[paranz]

you may be interested to read this ebook also:

telecommunication circuit design by Patrick D. van der Puije <-- very good book, very helpful

link:

http://mihd.net/1.212/Telecommunication.Circuit.Design.2nd.Ed.rar.html

[toasted siopao]

SWR meter schematic na working at accurate, may alam ba kayo?

[paranz]

hmm wala yata ako alam nyan 

[0b00000111]

gamit ko dati is yung National Semiconductor Cordless Voice Module + ginamitan ko ng Freescale MCU. http://www.national.com/news/item/0,1735,935,00.html . It has phone and data capability and more features... Yun nga lang mahal hehehehe....

dito ko ginamit

[paranz]

in college i used a National Instrumenr 16-bit PCI I/O board. Donated from CHED to our department.
ang liit ng board parang 56.7k internal modem lang ang size but cost about P105,000.00 each 

[0b00000111]

mahal talaga mga products ng NI

[Born2BeWired]

As an ECE instructor, i believe mas madali maggawa ng FM or AM transmitters for students. you can design one using 3 or more transistors. Marami schematic sa internet pero wala calculations other than just descriptions.

You will need a thorough knowledge on transistor amplifiers (common-base, common-emmiter, voltage-followers, multitransistor amps), oscillator circuits, maybe power amplifiers, also freq. response of transistors.

you will need an oscilloscope, 2 channels preferably. If you are building an FM transmitter, you might need 100-Mhz oscilloscopes. kung am transmitter, gamitin mo 4-quadrant modulator IC para madali connected to a power amplifier.

If I may add this tip:

 if you plan to use your wireless pair with microcontroller circuit, stay away from 27MHz or 49MHz band. Your RF receiver will be simply overwhelmed by the interference coming from the uC. Use ISM 433MHz (ISM: Industrial Scientific Medical band, unlicensed).

* You can use 27/49MHz band if you enclosed your uC with shielding case, with all wires coming out passing thru RFI filters. 

[paranz]

i did try several projects like that, using RC from toy cars and PIC microcontrollers. But i used rc clock for the microcontroller (150k-600+khz) so at best wala interference sa 25 MHz RC. i also tried as using 4Mhz crystal, somehow wala rin interference..

so additional tip: run the microcontroller at lower clock freq 

[Born2BeWired]

You are right in saying that lowering the frequency may help solve the problem. In fact, if the receiver has good selectivity and good spurious signal rejection, you may even minimize interference problems by chosing a crystal frequency with harmonics not falling within the receiver frequency band.

Good selectivity and rejection, however, can be found only in (more expensive) superhet narrowband type receiver, not in super-regenerative type that are the favorite of R/C toys.

Note that the effect of unwanted interference may only be a reduced control distance of, say 30% (100ft distance reduced to 70ft because of interfence). This is unnoticable in most cases. It usually becomes worse with increasing microcontroller clock frequency. In my experience, a zilog z8 MCU operating at 10Mhz generates enough broadband interference to render a 27MHz receiver on-board useless.