Just what is technobabble? Anyone who has watched more than an episode or two of Star Trek (any of the four different shows) has a pretty good idea, but I'll offer up a definition anyway. Technobabble is a technological description or theoretical explanation of technology, processes, or phenomena designed to depict a futuristic or more advanced understanding of said technology, processes, or phenomena while advancing the plot of the story. Lines from a couple recent episodes of Star Trek Voyager got me to thinking a little bit about what makes good technobabble in a Star Trek script. In my opinion, it must have certain characteristics:
In the episode Day of Honor two characters are marooned in inter-stellar space wearing environmental suits and need to contact the ship for a rescue. The following technobabble solution was stated: "If we interplex the comm systems in both suits, we might be able to create a phased carrier wave. Voyager would read the signature and know it's from us." What makes this good technobabble is that it encompasses a basic understanding of communication theory, uses vague words to describe the solution, and doesn't violate known laws of physics. With a stretch it even encompasses some continuity from Star Trek Deep Space Nine.
Being a professional Electrical Engineer who is also an Ham Radio Operator, I immediately surmised a specific solution the characters might have implemented despite a slight diction error in the line. In order to explain the solution, I need to explain a few basics about communications systems. Refer to the following block diagram:
Input Transducer: Converts an input source message into a form recognizable by the transmitter. The wide variety of possible information sources results in many different forms of input messages and input transducers. However, these messages may be categorized as either analog or digital. Analog messages may be modeled as functions of a continuous-time variable (for example, pressure, temperature, speech, music, images) while a digital message consists of discrete symbols (for example, text and numerical data). We shall call the output of the input transducer, the message signal. The most recognizable examples of an input transducer are a microphone and television camera.
Transmitter: The purpose of the transmitter is to couple the message to the channel. When coupling a message to a channel, it is often necessary to modulate a carrier wave with the message signal to produce a modulated signal. Modulation is the systematic variation of some attribute of a carrier signal, such as amplitude, phase, or frequency, in accordance with a function of the message signal. There are several reasons for using a carrier and modulating it: 1. for ease of radiation (and detection during reception); 2. to reduce noise and interference; 3. for multiplexing or transmission of several messages over a single channel. A transmitter typically employs a radiator or antenna to couple the modulated signal to the channel. Other functions performed by the transmitter typically include filtering and amplification.
Carrier: The carrier is usually a sinusoidal signal defined by x(t) = A(t)cos[wt + p(t)] where A(t) is the instantaneous amplitude (typically 1 for simplicity of the transmitter), w is the carrier frequency in radians/sec, p(t) the instantaneous phase deviation of the signal (typically 0 for simplicity of the transmitter) in radians, and t is the time in seconds.
Channel: The channel can have many different forms, the most familiar, perhaps, is the channel which exists between the transmitting antenna of a commercial radio station and the receiving antenna of a radio. In this channel, the transmitted signal propagates through the atmosphere, or free space, to the receiving antenna. Since communication systems on Star Trek have traditionally be referred to as subspace radios, one could surmise that subspace, whatever that is, is the channel used to propagate radio signals in the 24th century. Regardless of the medium of the channel, all channels have one thing in common. The signal undergoes degradation from transmitter to receiver. This degradation typically results from distortion, noise, and other undesired signals or interference characteristic of the channel.
Receiver: The receiver's function is to extract the desired signal from the channel and convert it to a form suitable for the output transducer. It may also demodulate, amplify, and filter the signal. Two important characteristics that determine the performance of a receiver are it's sensitivity and selectivity. Sensitivity is the receiver's ability to recognize and demodulate a weak signal while selectivity is the receiver's ability to filter the desired signal from interfering signals near the desired signal's frequency.
Output Transducer: The output transducer completes the system. This device converts the signal output by the receiver into a form desired by the user. The most recognizable examples of an output transducer are a speaker and television. The viewscreen on the bridge of Voyager also qualifies.
Okay that covers the block diagram. Now let's go over a few more important definitions.
Antenna Gain: A measure of an antenna's ability to concentrate radiated energy in a given direction. Antenna gain is measured in decibels (dB). An antenna that has 3 dB of gain over another is said to have twice the concentration of energy (or power).
Bandwidth: Bandwidth is the frequency variation of the transmitted signal. The more complex the source message, the wider the bandwidth of the transmitted signal.
Interplex: Being of or relating to a system of multiple circuits or transmitters combined to transmit a single signal.
Phased Array: An antenna configuration composed of a group of individual radiators which are distributed and oriented in a linear or two-dimensional spatial configuration. The amplitude and/or phase excitations of each radiator can be individually controlled to form a radiated signal of any desired shape (within the limits of the number of available radiators).
Repeater: A communication device which receives a signal on one frequency and rebroadcasts it on another. In Ham Radio, VHF repeaters are used throughout the United States to enhance mobile communications. A more familiar example of a repeater system is a cellular phone system.
Signal-to-Noise Ratio (SNR): The relative strength of a transmitted signal with respect to the inherent noise of the channel.
Spectrum Analyzer: A piece of instrumentation equipment used to measure the real-time amplitude of a signal versus the signal's frequency.
Wavelength: The distance a periodic signal (sinusoidal signals, carriers, are periodic) travels during the time it takes the signal to complete one period.
What do we know about the capabilities of the communication systems in the suits? From the episode, we certainly know the following:
In order for my application of the solution to work, we need to make a very important assumption. The assumption is that the each suit has at least two communication systems each with it own antenna. This assumption is backed up not only by prior episodes of Star Trek, but also by current designs of space based communication systems.
First, in the Deep Space Nine episode Destiny (it's the one where three female Cardassian scientists are assisting the DS9 crew in setting up a communications array through the wormhole and Sisko ends up escorting some rogue comet fragments through the wormhole as the result of an accident during the test). In that episode, one of the Cardassian scientists ran into an engineering glitch because Chief O'Brian replaced a big honkin' Cardassian transmitter with a smaller Federation transmitter, and its primary and secondary backups in order to bring the station's communication system up to Federation specifications. Apparently, the Federation replacements couldn't handle the power output of the equipment the Cardassian scientist brought for the test.
Next, let's consider the Galileo spacecraft currently orbiting Jupiter. It has two communications systems. One is hooked to a high-gain antenna and is designed for high speed data transfers. The backup system is hooked to a lower-gain antenna and transfers data much more slowly (pay attention to a following discussion on the impact of Bandwidth and SNR on a signal to understand why it's slower). Well, it's a good thing Galileo had a backup communication system because the high-gain antenna failed to open after launch.
Suffice it to say, it is reasonable to assume that each environmental suit would have at least two communication systems. Let's also make the following assumptions about the communication systems in the suits:
So what could have been the interplexing solution B'Elanna that implemented. She configured her suit to transmit a carrier signal on both transmitters and Tom's suit to function as a repeater. Or more specifically, receive one her carriers on the receiver of his first communication system, shift it's phase deviation with respect to her transmitted signal, and retransmit the signal on his second communication system. I figured Tom's suit was the repeater because he got the feedback. A communication system won't experience feedback unless it receives it's own transmit signal. Another block diagram (with input and output transducers removed for simplicity) shows the suit configurations:
In the above block diagram, both transmitters in Torres' suit would transmit the same carrier signal. The carrier transmitted by transmitter 1 would be received by receiver 1 in Paris's suit. Internally, the received signal is routed to transmitter 2 and phase deviation is added such that p(t) is a constant. A constant phase deviation simply shifts the carrier signal (remember the one equation I gave above) in the time domain--effectively creating a delay. In frequency domain it is called a phase shift. Therefore, the transmitted signal at antenna 2 of Paris's suit has a phase shift with respect to the signal at antenna 2 of Torres's suit. When properly oriented, the two antennas will act as a two element phased array.
In Day of Honor we never saw the transmit antennas of the environmental suits. That's not unusual, we've never seen the transmit antenna of a comm badge either. In fact, unless you've taken the remote control of your garage door opener apart, you've never seen the little coil antenna in there for transmitting your remote's signal to the opener.
So what would the proper orientation of the two antennas need to be in order to form a two element phased array? That depends. Let's assume that the antennas have the characteristics of a standard vertical antenna (like on a cellular or cordless phone). Well, phased array antennas are a topic requiring even more explanation than I've given here so far. Suffice it to say that separating the antennas by a quarter wavelength and setting the phase shift to 180 degrees would result in a mutual coupling of the two antennas to produce a gain of 4.3 dB in either direction along the line formed between the two antennas--you'll have to trust me on this. The strength of the signal has been tripled. Of course, the scene showed no signs of the characters moving the antennas into the proper position, but I'll accept that it wasn't necessary to show this activity to make the scene work.
Okay, so now we've introduced a nice bit of gain to our system. Why not transmit an audio signal instead of a carrier signal? The answer is power. It's limited and we want to stretch the signal. An speech signal has a much wider bandwidth than that a carrier signal--at least by an order of magnitude. The output power of the transmitter must be spread out over this bandwidth. Therefore, the carrier signal has an SNR at least an order of magnitude greater than that of the speech signal.
4.3 dB of gain and 10 times the SNR. Not bad.
Now that we've boosted the signal, just what was meant by Voyager being able to "read the signature" and know it was sent from Tom and B'Elanna? Well, an ideal transmitter would transmit only the desired signal and nothing but the desired signal. However, in real life, transmitters aren't exactly going to be ideal--even in the 24th century. All transmitters send additional harmonic and spurious signals in addition to the desired signal. Although significantly smaller in amplitude than the desired signal, the characteristics of these additional signals can be measured by a spectrum analyzer. To a trained eye, a Federation transmitter would emit a unique spectrum, or signature, when compared to the spectrums of other transmitter designs.
Now for the folks on Voyager to even recognize the signature, they have to be listening for the signal. Either they have one hell of a police scanner on the ship--cellular blocked of coarse, or procedures have set aside a specific frequency for emergency communications which would be continuously monitored for activity.
Finally, if they have a frequency reserved for emergency communications, then why not a panic button on all comm badges and environmental suits which would emit a periodic emergency beacon on said frequency. Navy pilots have such devices today when they eject and end up in the drink.
This does not invalidate any of the engineering I did to explain how to boost the signal from the suits, but it does explain how the signal could be detected quickly.
Corroded relays causing a ventilation system control panel to explode.
Relays to the ventilation system corroding because a deck was flooded with gas from a Nebula in the Year of Hell. Even today, except in the most high-power applications, there are many alternatives to electromechanical relays using a magnetic coil and metal contacts. These include solid-state relays and opto-isolators (a solid state relay controlled with a light source or light emitting diode instead of an electrical stimulus). Besides, as a matter of fact, it seems practical to me that ventilation system components would be hermetically sealed to isolate them from the environment they're controlling.
Plus, it's been well established in Star Trek that ship circuitry is based upon optical technology and not semiconductor technology. Optical computers have already been developed in the lab and there's plenty of work to be done before their technology is developed enough for practicality and cost-effectiveness. Someday optical circuits may be to the semiconductor what the semiconductor was to the vacuum tube.
The writer's could have just said the panel exploded as the result of battle damage.
Accepting that the transporter, replication, and holographic systems are some of the most far-fetched technologies introduced in Star Trek, I can think of a couple reasons why a crewmember on Voyager could communicate with another crewmember on a planet's surface or another remote location, but not obtain the ever elusive transporter lock. In fact, I can use some of the arguments I discussed in my self-absorbing lecture on space suit communication systems.
The first issue involves, power output, signal bandwidth, and SNR. Think of it. If a simple speech signal has an order of magnitude wider bandwidth that a carrier signal. What must the bandwidth of a transporter signal be when compared to the same reference? We're talking about all of the data necessary to convert an individual from energy to matter again. It is reasonable to assume that the power available to transmit such a complex signal does not increase proportionally with respect to the bandwidth of the signal. Therefore a lower SNR must be accepted and the fact recognized that more ideal conditions must be available for transport than for subspace radio communications.
The next issue involves the fact that the transporter system doesn't typically have a receiver at the destination to help filter and clean up the signals. The transporter really works more like a lens focusing light than a radio. All distortion correction must be done at the source rather than shared with the destination. Something tells me that this would make things more difficult too.
All considered, the transporter must also have a shorter range that the ship's subspace radio too.
I certainly hope those reading this article found it interesting. If so or if you have comments, E-Mail me at firstname.lastname@example.org.