Breaking News
Comments
Newest First | Oldest First | Threaded View
Larry Burgess
User Rank
Rookie
re: Adapt low-band ISM transmitters for high-band operation
Larry Burgess   7/13/2011 5:14:51 AM
NO RATINGS
To respond and add to WKetel's comments: Part of this experiment was aimed at understanding the behavior of switched amplifiers driving circuits that they may not have been designed to drive. The model we use at 434 MHz is one where the output tank circuit is hit with a 25% duty cycle (at RF) pulse train and it is well documented, but what happens if the tank circuit is tuned to twice the intended frequency and it is still hit with a 25% duty cycle pulse train?

Larry Burgess
User Rank
Rookie
re: Adapt low-band ISM transmitters for high-band operation
Larry Burgess   7/13/2011 5:05:56 AM
NO RATINGS
Good question about why one should try this for his application. You are correct in saying that there are a lot of ISMRF IC's around that work at 868 MHz, and some of them are already simple and inexpensive, as opposed to the more sophisticated ones that have shaped modulation, low phase noise, and high current drain. I think the motivation for this article was part lab experiment and part creative thinking for developing a very simple very inexpensive part in the future. - Larry Burgess

WKetel
User Rank
Rookie
re: Adapt low-band ISM transmitters for high-band operation
WKetel   6/29/2011 1:48:53 PM
NO RATINGS
This is an interesting analysis and a new(sort of) application of a technique that radio amateurs have been using since at least 1950, which is the oldest dated publication that I have that references it. Hams call it "frequency doubling" or "frequency multiplication", and they have used a similar technique to obtain multiples of 2x, 3x, and 5x the input frequency. One thing to note is that because the operation is quite nonlinear, any amplitude modulation of the signal is quite distorted. Now, to address the comments from titux, we should understand this in order to assure that we avoid unintentionally transmitting signals on frequencies other than the intended ones. This is a problem associated with all nonlinear amplification, which is usually cheaper, more efficient, and simpler than linear amplification. And most designers aim for cheaper, simpler, and more efficient.

titux
User Rank
Rookie
re: Adapt low-band ISM transmitters for high-band operation
titux   6/29/2011 9:16:31 AM
NO RATINGS
ISM RF ICs are offered as 'use it as it is' parts, leveraging on their fulfillment of functional requirements. So, many users never even get to know the underlying RF basics. This article appreciably sheds a light on what is below the surface and may be a good track for some lab excercise. From an engineering point of view, since there is plenty of ISM ICs designed for the 868/915 bands, the first question may be 'why should one try this for his application?'.

JanineLove
User Rank
Blogger
re: Adapt low-band ISM transmitters for high-band operation
JanineLove   6/28/2011 1:16:27 AM
NO RATINGS
Think you might give this a try? Leave your comments on the article or questions for the author here...



Flash Poll
EE Life
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More
Max Maxfield

Juggling a Cornucopia of Projects
Max Maxfield
Post a comment
I feel like I'm juggling a lot of hobby projects at the moment. The problem is that I can't juggle. Actually, that's not strictly true -- I can juggle ten fine china dinner plates, but ...

Karen Field

June 2014 Cartoon Caption Winner
Karen Field
13 comments
Congratulations to "Wnderer" for submitting the winning caption for our June cartoon, after much heated conversation by our judges, given the plethora of great entries.

Jeremy Cook

Inspection Rejection: Why More Is Less in a Vision System
Jeremy Cook
3 comments
Albert Einstein has been quoted as saying, "Everything should be as simple as possible, but not simpler." I would never claim to have his level of insight -- or such an awesome head of ...

Jeremy Cook

Machine Fixes That Made Me Go 'DUH!'
Jeremy Cook
21 comments
As you can see in my bio at the end of this article, I work as a manufacturing engineer. One of my favorite things that happens on a Friday late in the afternoon is to hear my phone ring ...

Top Comments of the Week
Like Us on Facebook
EE Times on Twitter
EE Times Twitter Feed

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)