modern oscilloscopes

Have you pushed the BW on that to analyze a sine wave for malformed results?

I find that many scopes start to distort a little when they near their Band limit. Also, the amplifier linearity is also one to question at any bw.

Jamie

On 14/02/13 04.03, John Larkin wrote: ...

...

Hi John

It is probably because that the DAC+lowpass filter use 1/x envelope compact supported ortogonal sinc-sampling base functions:

Please note that convolution of a signal with a sampling function - is equivalent to filter a signal with an appropriate lowpass filter - hereafter you can sample at regular intervals and send the sample to a DAC.

A better sampling is with Wavelet-scaling base functions - many biortogonal og ortogonal Wavelet-scaling functions exists. There exist Wavelet-scaling functions that is exponentially mathematically compact supported in both the time and frequency function space:

Moving at Wavelet speed: Wavelet modulation can help squeeze more out of existing networks:

Quote: "... Figure 1: Steep stop-bands ... The stop-band of Wavelet modulation is in excess of 40 dB than the stop-band of Fourier-based modulation techniques such as DMT and OFDM [implicitly using sinc-functions!]. This property provides many advantages over existing modulation techniques: ...

• Greater resistance to noise and interference opens up the whole pipe: only noise directly in the sub-band is of issue

• Easier equalization: equalization only need cover the sub-band

• Longer symbol time greatly increases microreflection immunity

• Less-noise polluting: wasted side band energy is not emitted

• Excellent separation and isolation of sub-bands

• No need for external filters. ... The data rate of a downstream wavelet channel is 170 Mbps, equivalent to

1024 QAM or 10 bit per Hertz per second modulation density. ..."

-

Wavelets 101 - Wavelets for Dummies (Non-Mathematicians):

Wavelets 201 - QAM OFDM Wavelets - A Relative Performance Comparison:

Quote: "... Comparison Table ..."

-

INTRA overview:

Quote: "... The modem modulation method called INTRA (INformation TRAnsformations) is based on Wavelet Theory. With INTRA, the data-rate for networks can be increased by a factor of 2 to 4 over the current state-of-the-art for LANs and MANs based on simulations. INTRA modems can achieve this remarkable performance at very low cost. ... The receiver for one channel is shown as a Surface Acoustic Wave Filter (SAW) followed by one comparator. There is no A/D converter or DSP in this INTRA receiver. ... Each wavelet extends over several symbol [= a Wavelet scaling function sample] periods. If the wavelets are orthogonal they are uncorrelated so there is no interference from other wavelets. Thus there is no Inter-Symbol Interference (ISI) and no Adjacent-Channel Interference (ACI). Wavelets can be generated and received by matched transversal (FIR) digital filters. Simulations show this all-digital design has no spurious response. ... The correlation process-gain of INTRA provides an inherent immunity to interference that is comparable to the jamming rejection of a conventional spread spectrum system, except that INTRA does not spread the spectrum. Conventional spread-spectrum wastes bandwidth in order to obtain this immunity to interference. INTRA does not expand the bandwidth with a spreading function --- in fact, INTRA spectra can overlap due to the properties of wavelets so it is more bandwidth efficient than any other modulation. INTRA's immunity to interference comes by spreading symbols in time rather than frequency, and since the time waveforms of wavelets can also overlap there is no penalty in data-rate. ..."

Tech archives INTRA Introduction:

Quote: "... Figure 1 ... [Instead of a comparator use use a flash-DAC - then you have a Wavelet scaling function sampled the analog signal:] In the illustration, the receiver uses an analog SAW filter and comparator to correlate the received waveform with the known wavelet shape. Here the sign of the correlation determines if a 1 or a 0 was received. ..."

Quote: "... The receiver's matrices contain the time-reversed wavelets so that the receiver's vector-filter computes the correlation between each orthogonal wavelet and the received signal to recover the DATA vectors. This is in fact the textbook form of an optimal MAP (Maximum Apriori Probability) receiver. Not only is INTRA an optimum receiver in this MAP sense, but it also has the following six very powerful features:

1. It can be self-equalizing by applying any adaptive equalization algorithm (i.e. LMS) to the vector filter matrices in the same manner as FSE.

1. Interference is suppressed, since the symbols are recovered by correlation.

2. FIR vector filtering (Tx or Rx) can be done in the analog domain with SAWs or CCDs, so no D/A or A/D converter or DSP is required at high rates.

1. Fractional bits per vector coordinate can be assigned according to SNR.

2. Since vector-filtering is a convolutional modulation, a receiver Viterbi Algorithm might provide error-correction without sending parity at the transmitter. (This is a potential theoretical breakthrough since conventional Trellis Coded 6.Modulation (TCM) sends parity, which wastes transmitted entropy and therefore lowers the potential data rate near the Shannon Limit.)

1. Vector-filters can be used for compression-less networking, a new concept described in PART 2. ..."

Technology Frequently Asked Questions:

Quote: "... Rainmaker Technologies? Wavelet modulation for CATV cable modems has zero computational complexity in both the transmitter and receiver. ... Q7. Does Rainmaker?s equalization method provide immunity to upstream interference?

A. While equalization helps, immunity to interference is an intrinsic feature of Rainmaker Technologies? wavelet modulation due to the gain realized during the receiver?s correlation processing. ... Q14. Does Rainmaker recommend interleaved block codes for Forward Error Correction Coding?

A. This may not be necessary because Rainmaker Technologies? solution has correlation processing gain. ... Q15. Can Rainmaker provide more details about immunity to RF Interference?

A. Rainmaker Technologies? wavelet cable modem is immune to interference in the sense that the error rate is still good. Rainmaker Technologies? solution doesn't look at individual samples. Instead, it compares wave shapes (correlates) over many samples for each symbol. It suppresses interference because non-Gaussian interference doesn't have the same wave shape as a wavelet. Rainmaker Technologies? solution has a gain in Signal-to-Interference Ratio (SIR) in the receiver. ... Q16. What else can Rainmaker Technologies? wavelet modulation do?

A. Calculations show that Rainmaker Technologies? solution should dramatically improve the data rate of wireless and twisted pair links compared to the current state-of-the-art. ..."

/Glenn

scopes

so

DAC? What DAC?

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation

Hey John,

When you changed out the flash memory in the SD-24 sampling head what did you need to do to initialize the new memory?

Thanks, tm

We copied the data from a good flash chip from another head, before we installed it.

I think we hacked in a socket, too.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation

scopes

so

Digital analog converter

scopes

so

In an oscilloscope?

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation

...

This image is on a PC - so I assumed it was a digital oscilloscope:

DSO as in?:

/Glenn

Do you still have the image and can you still program those devices? I have a sampler with a bad flash.

Thanks

:

ote:

DAC as in Digital to Analog Converter, not much use in an oscilloscope ADC as in Analog to Digital Converter, what you would find in a digital oscilloscope

-Lasse

scopes

so

Hmm, to drive a plotter printer?

Jamie

I think we have the image, and I could always pull the one that's socketed... if I can figure out which one it is. I'll ask Jonathan; he actually did it.

Our B&K USB programmer can read and write these things.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation

Digital scopes have ADCs, but the display is an LCD. The signals may be digitally processed, but not through a DAC.

But my point is that the scope makers have a choice of step responses, and many seem to pick a peaked, underdamped response to be able to claim more bandwidth.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation

My mistake - I meant an ADC. It was late for me.

The first CD-players had the same problem because of very steep output filters at mayby 20KHz. The DAC used 44,1 KHz.

Today oversampling is used combined with filters that are gradually damping the higher frequencies.

-

The test square signal had ringing, because of the steep input filter at the original ADC.

/Glenn

tm,

It's a 93C46. Give this one a try:

scopes

or so

Sure. DSOs have DACs and ADCs. At least the ones I've worked on do.

Both

Old school designs were close to a critically damped for step response but the marketing guys decided that specsmanship sells more kit.

--
Regards, 
Martin Brown

Thanks JW. Strange but that bin file is only 128 bytes. The 93C46 is a 1k device, right? I think the biggest problem with changing the chip is the self test fails on a bad check sum then everything halts. Hopefully John can burn one for me sometime.

I did find some parts on ebay and have ordered some. Meantime, I will install a good machined pin socket.

Regards, tm

Yup it's 1Kb, not 1KB. So 128 bytes is correct. The one I posted will get rid of your checksum error, but I think the cal constants may be stored in there as well, perhaps John may know better. Anyway If John can't program it for you, just give me a shout on the Tekscopes list and we can set something up...