Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: Prev 1 [2]   Go Down
  Print  
Author Topic: Flex - Advancing the Radio Art  (Read 15866 times)
K5TED
Member

Posts: 214




Ignore
« Reply #15 on: June 05, 2012, 08:15:12 PM »

"What do we SDR fans really want?"

This one wants a standalone SDR radio with knobs and a fully functional streaming web interface allowing multiple receiver instances on any band.

 
Logged
VE3WGO
Member

Posts: 395




Ignore
« Reply #16 on: June 08, 2012, 05:15:45 PM »

"This one wants a standalone SDR radio with knobs and a fully functional streaming web interface allowing multiple receiver instances on any band."

....but isn't that kind of what you get with most high-end dual receiver radios today anyway?  Knobs and software defined radio?  I think every one of the DSP-based radios for sale today qualifies as an SDR in its own right.  Perhaps the definition of SDR is a bit blurry, and for ham radio purposes can be taken to mean software-defined function menus. 

I have been working in the cellular base station radio design business since 1988. At that time, we were designing the first digital cellular radios for AMPS/TDMA (aka North American Digital Cellular).  Up to that point in time, all radios had been totally hardware-based, including the modem, control, and frequency generation functions.  We did it differently, and came up with a Motorola DSP-based AMPS + TDMA modem and Intel microcontroller, with the DSP software downloadable on a call-by call basis, and all functions of the radio controlled by the microcontroller, and settable by an external PDA or laptop computer.  We issued periodic software updates to take care of "improvements" (aka fixes).  Our DSPs were operating at symbol sample rates of 48 kHz, only a factor of ~4 slower than today's soundcard-based ham radio SDRs.  Our 1988 SDR radios cost in the neighbourhood of $1400 US to make.  We sold over 1.5 million of them to wireless operators around the world in the 1990s.  Not too shabby, right?

Since those early days, we have remained at the leading edge of radio design, and now make software-defined radios for CDMA, GSM, UMTS, and LTE.    Over 100 million sold, as Mickey D might say.

The main lesson here= A/D converter sample rate into the DSP is directly correlated with receiver performance.  It needs to rise as high as possible in order to maximize performance, interference rejection algorithm processing, and RF image rejection the most important parameter, since the offending image frequency is only (sample rate)/2 away.  In a soundcard system with a sample rate in <200 kHz range, the image can be well withing the same ham band the radio is operating in.  Whereas in the late 80s we were using DSP at baseband rates (48 Khz), today everybody's cellular basestation designs are sampling at IF, and that is close to 100 MHz, or direct conversion at many 10s of MHz.  It is the only way to achieve the desired targets of Image Rejection, Interference robustness, and operating bandwidth.  Tomorrows radios will use RF sampling, as people in the government, space, and military SDR projects are already working on.  That is the way to get absolute maximum performance in transmit and receive. IEEE has sponsored workshops on the topic a few times.

A soundcard-based SDR is not state of the art.

Tomorrow's true SDR will have RF sampling at the exact RF operating frequency, and all that you will need a PC for is to adjust radio settings.  For an RF sampling receiver chip example, see http://www.ti.com/product/lm97593#description  It samples receiver signals up to 300 MHz, which is really nice for hams, if anyone wants to try making one - it would be a barnbuster project. TI recently bought National Semiconductor, so there may be changes coming in exactly which chips they will eventually sell.

And what is totally ironic, is that one of those radios that is used in a cellular basestation, transmits about 500 Watts peak, and is highly linear, with a low noise receiver front end, semi-automatic interference rejection, transmit-spectrum analyser, automatic VSWR monitor, and software defined everything.  And it all costs in the same order of magnitude as a mid-high end ham transceiver from today's big 3.  Industrial strength radio, high performance, and it can be done.

So, whether you are a contester or a fanboy of either SDR or non-SDR, you do need to buy a radio with a high sampling speed DSP in order to get the best radio performance, and stop worrying about what the manufacturer calls it.  and "Tomorrow" you will be able to buy an RF-sampled SDR or RF-sampled DSP radio, depending on how your favourite manufacturer brands it.
Logged
ZENKI
Member

Posts: 1565




Ignore
« Reply #17 on: June 08, 2012, 06:07:53 PM »

Maybe  Apple  can design a DDC/DUC transceiver for the masses. It will use  IPAD's for the interface and use an advanced adaptive predistortion PA.

Ham companies unfortunately are obsessed with receiver numbers and nothing else. Heck, they cant even get something as simple as a calibrated  S-meter correct on any radio.
It would take  a outsider  that does not work in the narrow minded ham  engineering world to break the monotony of me-too engineering and sub standard product delivery that is so common in ham radio companies. However we cant blame the companies, they know they dealing with a bunch of Luddite hobbyists  stuck in the past that have more money than sense!

We can only blame ourselves, because at the end of the day when you have users  who have no idea what they want and have such a poor understanding of what technology can deliver, it is then no surprise we end
up with the expensive rubbish that we use. Hell if i payed 10, 0000 dollars for a radio and it cant measure  something as simple as a signal strength with a accuracy of  1 db  I am sucker and fool. Why would any manufacturer change
what they selling when they have such ignorant suckers for customers?  The  rapid price increases of ham radio equipment and the poor product performance, is actually the reverse of what is happening in the test equipment world. In the test equipment world performance is going up and the prices are going down. The same could be said for every area of the electronics manufacturing industry. Hams are good cash  flow cows for the ham companies and the poor quality products is a reflection of the low esteem the companies have for us as consumers. The ham equipment manufacturers have been stuck in a rut for the last 20 years, and now that they trying to get out of this rut, they expect us to shelve out a huge amount of money for backward products and their poor investment in good R&D and market research.

If I went into any test equipment shop today, I can buy equipment that can measure within 1 db of accuracy from 1hz to 3ghz for less money than I am going to pay for a top of the range ham transceiver. I am going to get knobs and a decent big TFT screen with great ergonomics for half the price of the useless top end ham radio wonder box. The technology in this state of the art piece of test equipment  is not much different to what is in most ham radio products, its just that the ham version has such poor execution, design, ergonomics and packaging.

We only have ourselves to blame for the mess  because we are not educated nor demanding enough to demand real change. If this was the automobile market most hams are still driving the  equivalent of a T model Ford instead of a state of the art German technology marvel masterpiece. We need to stop and look at ourselves in  the mirror, hams really need a technology shock therapy  treatment. We need to wake up and be more demanding technology aware  consumers.


"This one wants a standalone SDR radio with knobs and a fully functional streaming web interface allowing multiple receiver instances on any band."

....but isn't that kind of what you get with most high-end dual receiver radios today anyway?  Knobs and software defined radio?  I think every one of the DSP-based radios for sale today qualifies as an SDR in its own right.  Perhaps the definition of SDR is a bit blurry, and for ham radio purposes can be taken to mean software-defined function menus. 

I have been working in the cellular base station radio design business since 1988. At that time, we were designing the first digital cellular radios for AMPS/TDMA (aka North American Digital Cellular).  Up to that point in time, all radios had been totally hardware-based, including the modem, control, and frequency generation functions.  We did it differently, and came up with a Motorola DSP-based AMPS + TDMA modem and Intel microcontroller, with the DSP software downloadable on a call-by call basis, and all functions of the radio controlled by the microcontroller, and settable by an external PDA or laptop computer.  We issued periodic software updates to take care of "improvements" (aka fixes).  Our DSPs were operating at symbol sample rates of 48 kHz, only a factor of ~4 slower than today's soundcard-based ham radio SDRs.  Our 1988 SDR radios cost in the neighbourhood of $1400 US to make.  We sold over 1.5 million of them to wireless operators around the world in the 1990s.  Not too shabby, right?

Since those early days, we have remained at the leading edge of radio design, and now make software-defined radios for CDMA, GSM, UMTS, and LTE.    Over 100 million sold, as Mickey D might say.

The main lesson here= A/D converter sample rate into the DSP is directly correlated with receiver performance.  It needs to rise as high as possible in order to maximize performance, interference rejection algorithm processing, and RF image rejection the most important parameter, since the offending image frequency is only (sample rate)/2 away.  In a soundcard system with a sample rate in <200 kHz range, the image can be well withing the same ham band the radio is operating in.  Whereas in the late 80s we were using DSP at baseband rates (48 Khz), today everybody's cellular basestation designs are sampling at IF, and that is close to 100 MHz, or direct conversion at many 10s of MHz.  It is the only way to achieve the desired targets of Image Rejection, Interference robustness, and operating bandwidth.  Tomorrows radios will use RF sampling, as people in the government, space, and military SDR projects are already working on.  That is the way to get absolute maximum performance in transmit and receive. IEEE has sponsored workshops on the topic a few times.

A soundcard-based SDR is not state of the art.

Tomorrow's true SDR will have RF sampling at the exact RF operating frequency, and all that you will need a PC for is to adjust radio settings.  For an RF sampling receiver chip example, see http://www.ti.com/product/lm97593#description  It samples receiver signals up to 300 MHz, which is really nice for hams, if anyone wants to try making one - it would be a barnbuster project. TI recently bought National Semiconductor, so there may be changes coming in exactly which chips they will eventually sell.

And what is totally ironic, is that one of those radios that is used in a cellular basestation, transmits about 500 Watts peak, and is highly linear, with a low noise receiver front end, semi-automatic interference rejection, transmit-spectrum analyser, automatic VSWR monitor, and software defined everything.  And it all costs in the same order of magnitude as a mid-high end ham transceiver from today's big 3.  Industrial strength radio, high performance, and it can be done.

So, whether you are a contester or a fanboy of either SDR or non-SDR, you do need to buy a radio with a high sampling speed DSP in order to get the best radio performance, and stop worrying about what the manufacturer calls it.  and "Tomorrow" you will be able to buy an RF-sampled SDR or RF-sampled DSP radio, depending on how your favourite manufacturer brands it.
Logged
K5TED
Member

Posts: 214




Ignore
« Reply #18 on: June 08, 2012, 07:04:27 PM »

The Flex 1500 costs the equivalent of $100 in 1965 money. So does a FT-817ND.

Most hams like to use their radios to communicate, not give long distance bench tests.

Logged
Pages: Prev 1 [2]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!