Ex five telemetry signals each of bandwidth 1

Ex: five telemetry signals, each of bandwidth 1 k. Hz are to be transmitted simultaneously by binary PCM. The maximum tolerable error in sample amplitude is 0. 2% of the peak signal amplitude. The signals must be sampled at least 20% above the Nyquist rate. Framing and synchronizing requires an additional 0. 5% extra bits. Determine the data rate of resulted signal to be transmitted and then minimum bandwidth required to transmit this signal.

§ Line coding refers to the process of representing a symbol stream as electrical signals. *Some properties are desired in a line code such as: 1. 2. Low Transmission Bandwidth. 3. 4. Error Detection & Correction Capabilities e. g. Bipolar 5. Adequate Timing Content (Clock recovery): does the line code carry clock information ? Power Efficient : for a given Bandwidth and a specific detection error rate, the Transmitted Power should be as low as possible. Favorable Power Spectral Density (PSD) : it is desirable to get rid of low freq. components and DC shifts (codes that do this are called DC balanced, DC equalized, Zero-DC or Zero-Bias)

6. Transparency : A line code in which the bit pattern does not affect the accuracy of timing information is said to be Transparent. ØThe best way of analyzing a line code is to examine its PSD which gives valuable information about both power and bandwidth.

* Energy Spectral Density (ESD)

*The previous equation is a general equation for any line code. We now explore some of the popular Binary line code such as : 1. 2. 3. * Polar line code Unipolar line code ( on-off signaling) Bipolar line code (Alternate Mark Inversion)

* 1 1 1 0 1 1 To * 0 0 0 1

For polar line code * t

* EB

* EB

*Not Bandwidth Efficient *No Error Detection Or Correction *No DC value (DC = 0) *Most Power Efficient Line Code : for the same power it will result in the lowest Bit error rate (BER). *

* For RZ Pulses Timing Info can be extracted by Rectifying the polar signal which results in a periodic signal with clock freq. 1 1 1 0 1 1 To Rectifier 0 0 0 1

*One pulse shape that satisfies the previous requirement is : *If this pulse shape is used with polar line code, it is called Manchester , split phase or twinned Binary coding * t