Preview / Read the Current Issue of SSS
Volume 4 - Number 3 -- Spring 1996
[SS Chipsets Simplify SS Design]
[Data Randomizing ...]
[Go to Part 2]
SSS is proud to bring you our second online issue!
RUMORS & RAMBLINGS
SEND US YOUR "RUMORS" or Comment on "RUMORS" here!
- Noble Publishing, Tucker, GA recently announced the appointment of Gary Breed as President. Gary was with
RF Design Magazine as Associate Publisher. Randy Rhea, founder of Eagleware and Noble Publishing sees
Gary as a major addition and driving force for his tiger team of industry experts. For more information contact:
Noble Publishing, Inc. at +1 770-908-2320 or email: email@example.com
-- INTERNET: Noble Publishing Home Page -- Best of luck Gary!
- Hyperception, Inc., Dallas, TX recently introduced a new WWW Free DSP / Acquisition Hardware Locator Service
from its home page at Hyperception.You may also use email to access
this service by sending email to: firstname.lastname@example.org.
For more information contact Jim Zachman at: TEL: +1 214-343-8525 or FAX: +1 214-343-2457 or email:
- Corby Dawson of Lompoc, CA is a great source of used Atomic Frequency Standards at VERY LOW Prices! He
also has selected other test test equipment available. Give him a call at TEL: +1 805-736-0288, for more information
or a free circular. We got our Rubidium Frequency Standard from Corby for a steal!
- Loral Corporation and Bernie Schartz are at it again! They announced in early January that Loral has entered into a
series of strategic transactions with Lockheed Martin Corporation. Under the new agreement, Loral's space and telecommunications
activities will become an independent company under the new name, Loral Space and Communications Corporation (LSC). Loral's
defense electronics, information services, and systems integration operations were transferred to Lockheed Martin for 89.1
billion. LSC will begin business with an estimated value of 82 billion including $700 million in cash and no debt, and with
31% interest in Globalstar, 33% interest in Space Systems/Loral, and 22% interest in K&F Industries. As the managing
partner of Globalstar, LSC will continue to focus on the development of the Globalstar system. The system remains on-track
and on-schedule for launch in mid-1997 and commencement of operation in 1998. For more information contact Globalstar at
TEL: +1 408-473-5872 or FAX: +1 408-473-5750 -- Good Luck Bernie, you may need it!
- Digital Wireless Corporation, Norcross, GA recently announced its new WIT2400 SS OEM frequency hopping transceiver
with "12 dB More Receive Sensitivity" (more than a "wet Noodle?"). They also have the WIT915 with a full
one Watt output power available. For more information, contact them at TEL: +1 770-564-5540 or FAX: +1 770-564-5541 --
I really think they have a pretty good product!
- Besser Associates, Los Altos, CA continues to offer very well done courses of interest to all Wireless and SS designers.
Find out their latest offerings at: Besser Associates Home Page -- you may
also send them email: BesserCourse@delphi.com.
"Common sense is genius dressed
in its working clothes."
-- RALPH WALDO EMERSON
Here it is -- our SECOND online issue! Of course, we're a little late (again) with it! Better late than never they say.
The World Wide Web is a most interesting place! Since we went online and eliminated paper, we have been adding stuff to
this site in an effort to attract visitors. Most of our new features have been well received. Our hit rate has gone
from the low end at 20 or so hits per day in early January to over 200 per day recently. It's not a top 5% site yet --
but we're growing! The Web is so interesting, it never ceases to amaze me what you can find here. To help our
readers / visitors find their way around the Web, in their search for valuable information, we have added a number of new
SSS Online Subject areas, including:
- SS Tips & Quips -- Short articles, tips, sidebars, helpful hints and other stuff
- Ham Radio SS -- Now has the Latest ARRL SS FCC Petition & Comments -- we plan to add Ham
Hopper updates and other SS stuff of interest to hams & experimenters
- SS Apps -- Coverage of SS Applications including GPS, Wireless LAN, Telecommunication,
Industrial & Future predictions
- Design Tools -- Highlights of new hardware and software tools for the Wireless / SS designer
- New Chips! -- Spotlights of new ICs, ASICs and other "chips" for Wireless / SS
In addition, every week we update and add new material to the following three Subject areas:
- Weekly Feature -- Weekly Feature Story and Link presenting new, interesting,
important technology or application regarding Wireless and SS
- S/W Spotlight -- Weekly software spotlight featuring some new / interesting software for Wireless and SS
- H/W Spotlight -- Weekly hardware spotlight featuring some new / interesting chips, application or equipment for Wireless and SS
All of these additions were made to help you out! If you would like to see something else added here -- just email us:
email@example.com. We will compare your request with others and
probably add something that will solve your problem or appeal to your interests.
SSS Online is here to do two things:
As you should know by now -- we don't pull any punchs! After all this is a Commercial page! We are not here for
fun and games -- we are on the WEB to make a buck! Of course, while we are at it we feel it's our duty to "give back"
and provide useful information for all of you. Please call, write, email or send a carrier pigeon with your thoughts, comments and criticisms.
- Provide practical, useful information to the technical portion of the World Wide Web community.
- Bring RF/SS more consulting work!
Randy Roberts, Editor & Publisher, SSS Online|
Director, RF/SS Consulting
Rockwell 900 MHz Digital Cordless Telephone Chipset Product Review
Rockwell's state-of-the-art 900 MHz Direct Sequence Spread Spectrum DCT solution
provides all the components you need for long-range, secure cordless telephone
communications--with minimum development time and costs.|
As an OEM, you'll appreciate Rockwell's complete solution when it translates into lower
total system cost and faster time to market. By providing both baseband and RF devices,
system integration is minimized.
Your customers will appreciate the features--longer range, superior voice quality, higher
security and extended talk time.
Spread Spectrum is a coding technique for digital transmission which uploads the
information of a data signal over a wide frequency range, making the signal look like noise.
Data integrity, resistance to interference, and security are ensured using this technique.
Also, if the spread spectrum is used, the FCC allows more power to be transmitted--which
translates into longer range.
The power management of Rockwell's solution (baseband and RF) allows you to design
phones with 4 hours of talk time and 7 days of standby time. 16 million random security
codes pose quite a challenge for eavesdroppers who want to hear the conversation. Baby
monitors and garage door openers will no longer disturb your customers' phone
Plus: No more channel changing. Rockwell's technology does it for you, automatically
finding the best channel at any given time.
All of this, plus Rockwell's proven support and development tools in place, ensures the
lowest total system cost and the quickest time to market.
And it's a safe investment because you know Rockwell is a company you can count on to
grow with you well into the future.
- Baseband RDSSS9M Device Set
- Comprised of a voice Codec and an ASIC (which consists of a direct sequence
spread spectrum modem, an ADPCM engine, a controller, RAM and ROM).
- Receiver, RF100
- A monolithic direct conversion receiver which includes a low noise amplifier (LN)
quadrature double balance mixers, baseband filtering and a variable gain amplifier (VGA)
for a complete antenna-to-baseband I & O demodulator.
- Transmitter, RF101
- A monolithic device which includes a double-balance mixer, buffered LO port and a
power amplifier. The power amplifier has a three-stage, digitally selectable output power
of 1 mW, 10 mW, and 100 mW
- R900DCTM, Direct Conversion Transceiver Module
- A direct conversion radio module optimized for time division duplex (TDD)
operation, provides a clean connection to the baseboard modem and controller for receive
and transmit data and control.
Rockwell's SS DCT "Block Diagram"
SS Chipsets Simplify SS Design
By Randy Roberts, RF/SS Consulting
The Current Crop of Baseband SS Chips Can Help or Hurt The SS System Designer!
In the last year or so a number of new chipsets for SS signal processing have been announced. Some of these chips
are very good -- some are not so GREAT! How do you choose the GOOD from the BAD?
A few years ago CYLINK and O'Niel Comunciations (now out of
business) marketed their post detection de-spreading ASICs. I think quite a few people jumped on those chips --
but, were they in for a surprise! Not only did the FCC change Part 15 SS rules, but shipping these products
almost gave SS wireless products a bad name! Does the latest generation of SS chipsets really work? Are these
chips easy to use? Will these new designs find customer acceptance in the marketplace? This article will attempt
to answer some of these questions. SSS Online will try to save you time, trouble and perhaps even some real
embarassment with this preview!
New SS chipsets are available from IMEC.
Stanford Telecom AMI
and ATMEL / Wireless Logic also have come out with SS Chipsets
for specialized, niche markets. Seattle Silicon and others have had baseband chipsets out for some time.
There are a lot of chips on the market, aren't there?
We at RF/SS have designed a couple of DS SS radios with the the STEL-2000A and find it a very useful,
if not difficult chip to use. It is capable of baseband data rates up to 2.048 Mbits per second (E1 speed)
and can do PSK/DPSK/QPSK/DQPSK. While not for newcomers to the SS world, this chip PERFORMS!
RF/SS has been talking with Harris and is trying to become
a Technical Design Rep for them. They have loaned us an HSP3824 evaluation board, a handful of sample chips
and have promised evaluation boards for their other chips. In the next few weeks we will have completed a
full evaluation this promising new chipset and we will report our results right here!
IMEC has also talked to us about being a sort of
Technical Design Rep for them. They have formed a new company, SIRIUS, to market their new Baseband
SS chips in the USA.The specs on their chips are superb! They also have promised us a set of evaluation
boards for their chips. I'm hoping to complete a thorough evaluation of their stuff in the next month.
A recent client of ours has asked us to help him finish his wireless data radio design which uses the
ATMEL / Wireless Logic digital cordless chipset. We are still
busy helping him out, but our first impression is stay away from it! Wireless logic over a year ago
promised us evaluation boards, etc. and NEVER Delivered! We do have the complete data package on this
chipset -- but their design includes a great deal of "Proprietary" firmware for an 80C51 generic
microprocessor needed to supervise / run their chip. I have heard from a number of people that this
chipset just does not live up to all the hype that's been published about it. Besides, ATMEL doesn't
answer their phone most of the time and DOES NOT support this product. The ONLY support available for
the chip is from Wireless Logic in San Jose, when they are not in Taiwan!
I've heard great things about the Rockwell DCT
chipset reviewed above. But when I tried to get price and delivery information I called four diferent places --
I still did NOT get the information I needed! Of course, I wanted pricing only for quantities up to 5000 per
year or so -- I probably didn't even trip their sales least significant bit! Still the Rockwell chipset appears
to be a real technical performer for DCT type applications -- you should check it out!
QUALCOMM and OMNIPOINT
are also developing (or have developed) CDMA SS chipsets, to meet their respective IS standards -- I understand that
QUALCOMM is peddling theirs in Japan -- maybe before long they'll both find out there is a market right here!
AMI is selling various versions of its basic SX043 SSIC -- a part of
its WavePlex family of wireless products. Other than being slightly high priced, these chips seem to be very good!
AMI sells a set of evaluation boards for these chips -- so early design familiarity can be gained almost
painlessly. Expect to pay $500 or so for the eval boards, but they do include software and are easily interfaced
to PCs! Total functionality and flexibility is built in to these chips. You can buy a full duplex transceiver
chip or seperate half duplex transmit and receive chips from AMI. This chipset's design is very well
thought out and very useful across a wide range of data rates, processing gain and market niches. I predict
that if AMI finds the right price point, these chips will be real winners!
The job of the SS system designer has certianly been made easier with the introduction of these new SS
chipsets. But, as always -- CAVEAT EMPTOR (BUYER BEWARE)!!! Some of the available chipsets
are more than a challenge to make work! If I had to recommend a direction for choosing one of these new
chipsets -- I would go with an established vendor who has good support and / or a second source! Good
luck -- gentlemen, fire up your SS Design Engines . . .
Contributions: Data Randomizing with Pseudo-Noise Coding Techniques
Providing important information for today's SS system designer, this article is based on
Mr. C. R. Netherton's original application note which was done in the early 1980s.
By C. R. Netherton, Decom Systems
Pseudo-Noise (PN) randomizing of NRZ data enables the user to effectively
record 30,000 Bits/in/track/on an analog tape recorder, with a Bit Error
Probability of 10^6 or less. In the Wireless and SS world, data randomizing
is commonly used to meet the FCC's mandated level discrete "peak"
reduction in the output spectrum of a DS signal's frequency spectrum. In
essence, the PN randomizing process generates a data stream which is
characterized by a 50% transition density, regardless of long strings of
data ones or zeros. This characteristic overcomes the "baseline gallop" or
droop degradation that classical NRZ codes suffer, when recorded on
magnetic tape. It also ensures that the DS signals output spectrum looks
The PN generator is an n-stage shift register, employing modulo-2 (half
adder) feedback, as shown in Figure 1. NRZ data and the PN generator are
multiplied, as shown in Figure 1, to inform the randomizer and undergo
the inverse divisidn process, in an identical decoder, to form the
Figure 1: PN Data Randomizer & De-randomizer.
The data transmission code remains NRZ so that the optimum 0.7 bandwidth
to Bit Rate ratio is maintained. The PN encoding process is a 100%
efficient code, in that there are no added bits and all transitions occur
in phase, with a times one clock. Typically, an 11 bit, 2047 bit
(2^11 - 1) PN sequence is utilized in the randomizing process. Other
lengths can be used, but, generally, they do not provide any significant
The arithmetics of the PN data process are straightforward. The commutative
property of an "EXOR" process enables the derandomizer to synchronize to
the incoming data within (12) data bits, regardless of the initial power up-state
of the individual randomizer and derandomizer shift registers.
Obviously, nothing is generally gained without some penalty. PN
randomizing of NRZ data does suffer from an error multiplication process,
which essentially translates into about a 0.5 dB Bit Error Rate loss,
versus conventional NRZ. However, when you consider the increase in data
packing denisty on tape, the virtual elimination of "baseline gallop"
and the increased ability to operate at much lower synchronization
thresholds and data transition densities, one must consider the 0.5 dB
penalty a small price to pay, especially since other highly publicized
codes require substantially higher data bandwidths and bit error
In today's DS system designs these PN randomizing techniques provide
a convenient means of meeting the FCC's rules at the small cost of having
to re-synchronize the randomizer, if several uncorrected bit errors in a row
are generated in the receiver.
C. R. Netherton, "An Optimum Use of Bandwidth Via
Pattern Conditioning", Decem Systems, Inc., 1977, San
C. A. Castle & J. H. Stein, "Data Randomizing Shrinks
HDR Recording Hardware", Sangamo Weston, Inc., 1977,
E. L. Law, "Experimental Comparison of Pulse Code
Modulation Codes for Magnetic Recording", Instrument-
tation Department, Pacific Missile Test Center, 1977,
Point Mugu, California
D. A. King, "Comparison of PCM Codes for Direct
Recording," International Telemetering Conference,
1976, Los Angeles, California
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