Aeroflex Fastbit
Error rate analyzer - wireless numeral
communication
test facility
The
majority engineers and technicians "the error rate" (BERT) and the
correlation test are extremely familiar regarding the terminology. The error rate
test essentially is outputs a known data position class for to measure the
equipment, then the capture and the analysis from was measured the equipment
returns data stream. In order to enable the different instrument to have the
same test result, frequently applies one kind of special pseudo-random
sequence, this is a seedling source to the communication profession definition
standard.
Several
were different to the BERT test measuring appliance entered each kind of area
of technology, used in to survey the system-related or the part performance. If
the agreement analyzer, is one special-purpose test method, does not have the
versatility, but may simple and direct and effectively tests the error rate.
When, engineers design the wireless system, needs product under this kind of
environment performance which one kind fast, the precise method simulation
basic wireless communication channel disturbance (for example noise and weaken)
and the confirmation designs. Appraises set of unique wireless systems is the
extremely complex work, but if all now uses the digital modulation plan all
considered on was more complex.
Regarding
wireless system, not only needs to test harms the code length, moreover had to
pay attention to any type the background noise to create so many has harmed the
code. Therefore, the wireless test usual request appraisal error rate and the
different level simulation background noise correspondence relations, the noise
(each energy or ' bit SNR ' (takes a seat signal to noise ratio) by Eb/No compared to noise density) to express. (Attaches the
white gaussian noise) using AWGN to the radio
equipment rep in, may produce expresses ' BER– Eb/No
' the curve: Usually is called the waterfall curve (water curves). The
waterfall curve expressed error rate BER with between the background noise
relations which unceasingly reduces. The waterfall diagram of curves finally
tests the result, is the quite wireless system performance important attribute.
Responsible engineer, they most direct goal effectively has the test result,
and carries on the credible comparison. Therefore, understood the noise jamming
the possibility distributes may effectively carry out the test work. Puts
briefly, he may in the test time and between the expectation fiduciary level
and the precision level which may accept makes the compromised choice. When
tests completes, the test confidence and the precision may apply the waterfall
curve, therefore this curve may use in the credible quota comparison.
This
article, through analyzes the question which this kind of test faces, in detail
described the demand which now tests, simultaneously elaborated Fastbit the FB100A error rate reflectoscope
reflector and the FB200A noise occurs with the channel disturbance simulator
takes the test metering equipment the important performance.
A communication channel
model
Error
rate test and FB100A measuring appliance
Aeroflex uses in the wireless data
communication test Fastbit series product is the
ideal measuring appliance, uses in to work in the general wireless
communication domain researches and develops engineer, regardless of they are
the design or appraise each different digital modulation way, or designs each
kind of aperiodic regulator and the receiver. Which
kind of situation no matter is, they can feel very many convenient place,
because this product simultaneously supports serial and the parallel
communication, may compile the 4M byte data character to flow, to attach the
memory which the 4M byte may compile to use in to pack the data or the frame
structure data.
FB100A
is researches and develops engineer to design, it ill uses in the low end to
harm the code test and the open country protocol analysis confirmation. In
FB100A contains the function, like the test ' the package ' and ' the frame '
harms the code the test ability, uses in to define and to analyze the long
sequence the big memory space, enables it to carry on in the price with the low
end BER test facility the competition. FB100A ' is programmable ' the ability
to cause it to research and develop engineer extremely to have the value,
because it is not defined in some specific agreement. FB100A certainly is not
the design uses for to substitute some special-purpose test chamber agreement
analyzer, also cannot substitute expensive, is high
speed (Gbs) (for example the SONET system to develop
harms the code test which laboratory needs). FB100A may provide 100Mbs the
serial data stream and reach as high as the 160Mbs parallel data stream.
Therefore FB100A is these need flexibility and the high performance but budgets
tense laboratory engineers the ideal choice.
The
most low ends harm the code reflectoscope reflector
only to take the data stream generator the subordinate function, even if has
the memory very to be also small - only can use in PRBS (pseudo-random code)
the serial data stream production and the analysis. The most agreements
analyzer just like its name - only can have and analyze some specific sequence.
FB100A has provided the outstanding performance in this aspect, regardless of
user from definition sequence, or the instrument provides each kind of standard
PRBS sequence, its INSTALOKTM synchronization technology may provide the data
position class the fast synchronization and harm the code analysis.
FB100A
is in sole possession of the INSTALOKTM technology has contained fast two steps
of processing, regardless of PRBS data stream whether is implanted the frame
structure the payload, all may provide special frame structure forehead
synchronization and fast PRBS data stream synchronization. Moreover, the PRBS
data stream (namely first payload beginning) will start in the first frame
structure forehead end point, terminated in the frame structure payload end
point, causes the next structure forehead seamless continuous emission, then partially will continue in this payload from on end
point to transmit the PRBS sequence. Thus, the complete PRBS sequence may
transmit in the frame structure, completely does not have early in the BER test
limit. Therefore, has realized the simple establishment and the test, has
avoided the complex question which other instruments meets, like designs and
installs exterior logic circuit or the subsystem and so on.
FB100A
INSTALOKTM technology another is in sole possession of the function is it provides
' the character ' (byte width information) and ' the block ' the error rate
test. When ' the character ' represents the frame structure forehead, is all
neglected in forehead all positions, thus may simulate in the agreement the
frame structure forehead masking function. In parallel data transmission, '
character ' each may program and regard as an independent channel, harms the
code test to be possible to aim at ' the character ' or in 8 channels wilfully. Therefore, regardless of is analyzed the data is
the data position class, the byte width ' the character ', ' the block ' or the
frame and the frame structure forehead, all may carry on comprehensive and the
precise error rate test.
FB100A
(Divisor according to with outside clock port and its base complement) also has
two ' the port ' or ' the channel '. These extra ports may serve as or two
attachments pilot wires, namely ' frame structure synchronization ' channel and
its base complement; Or single channel ' the frame structure ' the synchronization
channel sch and the attachment single channel ' the
frame structure data is effective ' the target synchronization pilot wire.
These attachments ports may use in to test contain these pilot wires in the
design the simple data receiving set, avoids increasing the earlier period the
hardware investment.
The
FB100A another important performance is the measuring appliance internal data
generator and the data analyzer may serve as the independent measuring appliance.
The generator produces the data may be different the data which analyzes to the
analyzer. When when needs to analyze from is measured
the equipment (but is not the signal which FB100A) sends out, this is an
important tool. This performance is because in FB100A the generator and the
analyzer have separately used the independent 4M byte memory. Regarding
multi-purpose ' the pilot wire ' the function, the FB100A data generator has
the attachment the 4M byte programmable memory, uses in frame structure
synchronization sequence which is in sole possession of.
Finally,
FB100A has provided the logical connection contact surface many kinds of
different choices in physical level aspect multi-purpose for the user. In the
serial communication way, the standard output provides TTL and ECL, or TTL and
PECL logic level. The parallel communication way, the user may purchase each
kind ' POD ' to choose, including byte width data and pilot wire. These
parallel ' POD ' provides through the FB100A standard physics logic connection
the subscriber's equipment the connection. The connection includes: Uses SPI
(same frequency serial interface) MPEG, ASI (asynchronous serial interface), or
RS422, but also has the more general serial data transmission sdt, like RS232, RS449 and HSSI, contain like TTL and the
LVDS logic level. When joins general equipment the and so on data generator and
agreement analyzer which starts to mention function, the FB100A above
performance caused the simple BERT test facility to be allowed to become the
function formidable communication analysis tool.
AWGN and Gauss probability analysis
Theoretically,
you may survey the infinite long time to obtain the precise error rate test
result. However, you need the relatively short time to carry on the test in
fact. Therefore, the real BER statistics possibly obviously is higher than or
is lower than your test result. In the actual test, engineer uses harms the
code meter to obtain the error rate test result, but this result is only in a
probability statistics sample. Must appraise the system error rate, but also
needs to determine its precision scope as well as this precision scope
confidence (probability). Also some one kind of situation: After period of time
tests, have not appeared harm the code, by now how appraised the error rate?
Whether said this set of system is the zero error rate system?
Through joins the known statistical
probability the weight to the system in, you may harm the code through the
known probability distribution description the occurrence. The use probability
distribution, you may simply individually test with the confidence level level and the operational accuracy estimate description.
This method may in be possible to accept indefinite
result under, obtains the test result in the short time which may duplicate.
Through the probability statistics computation, we have established the
confidence level (confidence level), the expectation precision (target
accuracy), the theory error rate (lowest BER of concern), as well as must test between
the time the relations. Carries on the hypothesis to the corresponding
parameter, may obtain the test result which we needs. Regarding the zero error
rate test, may obtain in the credible error rate through the computation
limited line (Max the BER line), uses for to appraise system the error rate.
The waterfall curve and the test needs the time estimate
Usually,
the test result presents is the waterfall curve, the demonstration error rate
and the drop background noise relations. Some waterfall curves are assign the
theory which the modulation way is lowest may achieve limited line. These
theory waterfall curves have provided the estimate test time beginning. You
test the error rate was equal to or is higher than this level. Uses the actual
signal, the test error rate can approach the theory line, or obviously is
higher than. Through some initial tests, you may test this error rate, if is
essential, makes a new curve to represent expectation the error rate.
Regarding
the curve in you hoped the test each spot, takes the theory or the expectation
error rate substitution equality the actual error rate, you may the precise
estimate test time. You may inspect these estimates, determined which select
the most colored time. Similarly, the confidence may establish is a fixture,
through in the adjustment goal precision and the credible error rate limited
line, you may control the estimate time, thus the test time may establish as
the optimum condition.
This
kind of estimate work, causes the test the result to be reliable, satisfies the
test the request, but does not waste the test time. When tests finished, you
may carry on the analysis to the test work. You may apply the computation
precision to each error rate survey, found in the error rate the pilot wire to
apply to each unmistakable yard test. You may apply these tests the test result
the waterfall curve, may carry on more reliable and the quota comparison.
Before measuring appliance FB2000A is in sole possession of the test contact
surface, may individually test or a group tests, to the precision, the
confidence and the test time carries on the adjustment. Chart 2 demonstrated
this contact surface –
direct-viewing way to be allowed through the graph contact surface choice or
the input.
Establishes the confidence in the wireless data communication test
Regarding
the wireless system, in the test the confidence and the precision difficulty
with understood in some kind of procedure. However, through the flowered time
carries on these estimates before the test, carries on the analysis after the
test, you will reduce the complete test time, the test result are more reliable
also quantitative.
Before
all tests, determines about the confidence and precision all parameters. Decides the error rate limit. This time, you do not need to
survey any Eb/No value the lowest error rate. Using these Eb/No test point
determination test time estimate.
Receives,
according to test result which can accept, adjustment confidence, precision and
error rate limited line , fills in the test plan. Then, uses these parameters to calculate the conclusion test the
standard. This standard expressed harms the code quantity and the
unmistakable code figure for each Eb/No test point
request.
When
test conclusion, may applies the confidence and the
precision in the survey to carry on the waterfall curve test result the
fail-safe analysis.
FB100A
and the FB2000A instrument provides Windows NT the graph contact surface
control and the graph window, automatically demonstrates the error rate - time
diagram of curves, including target function and attachment many kinds of
traditions form data result. In addition, when FB100A and the FB2000A two
measuring appliances unions in under, the error rate - Eb/No
test is simplified. Is in sole possession of the cartography procedure provides
a body the test and the test result demonstrated (see Figure 3, one kind of
typical waterfall curve draws charting, originates to Fastbit
100 and the 2000A measuring appliance).