All Figures

$\begin{figure} \par\epsfig{file=h4417f1.eps,height=17cm}\end{figure}$ Figure 1: Long term average profiles of J1022+1001 at various radio frequencies. Profiles at 328, 382, 840 and 1380 MHz are from our present observations. All the other profiles have been taken from Kramer et al. (1999b) and references therein. Bandwidths of these observations are (from 328 MHz to 4850 MHz) 10, 10, 10, 10, 80, 80, 40, 40, 80 and 112 MHz, respectively.
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In the text

$\begin{figure} \par\epsfig{file=h4417f2.eps,width=8.5cm}\end{figure}$ Figure 2: Normalised component amplitude ratio R as a function of radio frequency. A value of $0<R\le +1$ indicates a dominance of the leading component, while for $-1\le R<0$ the trailing component is stronger. There is a strikingly systematic behaviour, with a minimum at a frequency of about 800 MHz.
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In the text

$\begin{figure} \par\epsfig{file=h4417f3.eps,width=15.5cm}\end{figure}$ Figure 3: Contour plot of pulse intensity as a function of pulse longitude and observing frequency for an average pulse profile constructed with 8 min of time series (approximately 30 000 pulses) in all the 16 channels each of 5 MHz width. For clarity, height of the second component ( $h_{\rm 2}$ ) has been normalised to unity in all the average pulse profiles (right-side vertical contour strip). The five inserts (from bottom to top) correspond to average profiles in channel numbers 1, 5, 9, 13 and 16. Contour level steps are in terms of root mean square error (see Eq. (1)). "Solid'' contour indicates the region where $h_{\rm 1}/h_{\rm 2} \ge 1$ . This figure has been plotted in the same style as Fig. 8 in K99 for easier comparison.
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In the text

$\begin{figure} \par\epsfig{file=h4417f4.eps,height=19cm}\end{figure}$ Figure 4: Average pulse profiles as a function of time in four different frequency channels. Each average profile was created with 8 min of time series. The four columns correspond to frequency channels with centre frequencies of 1382.5, 1407.5, 1412.5 and 1417.5 MHz, respectively, with a channel width of 5 MHz. The fractional height of the first component ( $h_{\rm 1}/h_{\rm 2}$ ) is also given for each profile, along with its deviation from the lowest ratio value (1st column, 2nd profile from top, ratio of 0.77) in terms of root mean square error (Eq. (1)). See text for details.
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In the text

$\begin{figure} \epsfig{file=h4417f5a.eps,height=9.8cm,angle=-90}\vspace*{0.5cm} \epsfig{file=h4417f5b.eps,height=9.8cm,angle=-90}\end{figure}$ Figure 5: Component amplitude ratio as a function of time (X-axis) and radio frequency (Y-axis). Each point corresponds to a time length of 8 min. Top panel corresponds to the observation at 1380 MHz, and the bottom panel to 840 MHz. Contour levels, in steps of root mean square error (see Eq. (1)), are indicated with different line styles for clarity. In the top panel, from the lowest contour level (white colour), the line style goes as "solid'', "dash'', "dot-dash'', "dot-dot-dash'', "dotted'', and "solid''. The highest contour level corresponds to the darkest gray scale point. In the bottom panel, as the signal to noise ratio is not as high as that of the top panel, there are only three significant contour levels.
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In the text

$\begin{figure} \par\epsfig{file=fig6.ps,height=16.2cm,angle=-90}\end{figure}$ Figure 6: Distribution of frequency and time scale lengths. Only the data set at 1380 MHz was used for this plot. As the plots show, a range of frequency and time scales are seen.
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In the text

$\begin{figure} \par\begin{tabular}{cc} \epsfig{file=h4417f7a.eps,height=8.1cm,an... ...90} & \epsfig{file=h4417f7b.eps,height=8.1cm,angle=-90}\end{tabular}\end{figure}$ Figure 7: Distribution of height ratios of the two components observed at 840 MHz (left) and 1380 MHz (right), for each 8 min average profile in each 5 MHz frequency channel. Horizontal error bar in the top right corner indicates 1 $\sigma$ error. The total extent of the X-axis (from one extreme height ratio to the other) spans over several times the error bar, and hence the profile variations are statistically significant. See text for details.
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In the text

$\begin{figure} \par\epsfig{file=h4417f8.eps,width=8.5cm}\end{figure}$ Figure 8: Top panel gives the average pulse profile of PSR J1022+1001 at 1420 MHz (solid line), the average linearly polarised intensity (dashed line), and the average circularly polarised intensity (dotted line). The bottom panel shows the position angle of the linearly polarised emission component as a function of pulse longitude. See text for details.
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In the text

$\begin{figure} \par\epsfig{file=h4417f9.eps,width=7cm,angle=-90}\end{figure}$ Figure 9: Linear polarisation position angle as a function of pulse longitude. "Dash'' line shows the unperturbed curve, and the dotted line shows the curve after taking into account the effect of aberration and magnetospheric return currents. $r_{\rm em}$ & $R_{\rm LC}$ indicate emission height and light cylinder radius, respectively, and $(J/J_{\rm GJ})$ is the current in terms of Goldreich-Julian value. (reproduction of Fig. 5 of Hibschman & Arons 2001). The point with longitude value zero represents the closest approach of magnetic pole to the line of sight.
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In the text

$\begin{figure} \par\epsfig{file=h4417f1.eps,height=17cm}\end{figure}$	Figure 1: Long term average profiles of J1022+1001 at various radio frequencies. Profiles at 328, 382, 840 and 1380 MHz are from our present observations. All the other profiles have been taken from Kramer et al. (1999b) and references therein. Bandwidths of these observations are (from 328 MHz to 4850 MHz) 10, 10, 10, 10, 80, 80, 40, 40, 80 and 112 MHz, respectively.
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$\begin{figure} \par\epsfig{file=h4417f2.eps,width=8.5cm}\end{figure}$	Figure 2: Normalised component amplitude ratio R as a function of radio frequency. A value of $0<R\le +1$ indicates a dominance of the leading component, while for $-1\le R<0$ the trailing component is stronger. There is a strikingly systematic behaviour, with a minimum at a frequency of about 800 MHz.
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$\begin{figure} \par\epsfig{file=fig6.ps,height=16.2cm,angle=-90}\end{figure}$	Figure 6: Distribution of frequency and time scale lengths. Only the data set at 1380 MHz was used for this plot. As the plots show, a range of frequency and time scales are seen.
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$\begin{figure} \par\epsfig{file=h4417f8.eps,width=8.5cm}\end{figure}$	Figure 8: Top panel gives the average pulse profile of PSR J1022+1001 at 1420 MHz (solid line), the average linearly polarised intensity (dashed line), and the average circularly polarised intensity (dotted line). The bottom panel shows the position angle of the linearly polarised emission component as a function of pulse longitude. See text for details.
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